GMAT Focus Practice Exam Question Review

A bank has 2 paper shedding machines, one large and one small, to shred sheets of secure waste paper, all of which are the same size. The large machine shreds sheets at a constant rate that is 5 times the constant rate of the small machine. How many minutes would it take the small machine, working alone at its constant shredding rate, to shred n sheets of the paper?(1) Working together at their individual constant rates, the machines could shred n sheets of the paper in 40 minutes.(2) n = 1,200

Data Sufficiency

4. A box contains exactly 7 fuses, 3 of which are defective and 4 of which are not defective. In the bar graph above, the left and middle bars are the same height and the right bar is half this height. The heights are intended to represent, respectively, the probabilities of obtaining 0 defective fuses, exactly 1 defective fuse, and 2 defective fuses when 2 fuses are randomly selected without replacement from the box. However, 1 of the bar heights is incorrect. The correct height is k times the height shown. Which of the following choices for the bar and the value of k would result in an accurate representation of the labeled probabilities? A. Middle bar; k = 1/2B. Middle bar; k = 2C. Left bar; k = 1/2D. Left bar; k = 2E. Right bar; k = 2

7 fuses (3 def, 4 Ndef) are in the box, from which a random sample of 2 fuses is selected.Left column:P(0 def) = P(Ndef & Ndef) = 4/7 × 3/6 = 2/7Middle column:P(1 def) = P(def & Ndef) + P(Ndef & def) = 3/7 × 4/6 + 4/7 × 3/6 = 4/7Right column:P(2 def) = (def & def) = 3/7 × 2/6 = 1/7According to the probabilities above, the ratio of the heights of the columns should be:Left : Middle : Right = 2 : 4 : 1We see that, in the graph, the heights of the left and right columns are in the correct ratio of 2 : 1. So, the height of the middle column should be changed.If we double the height of the middle column by multiplying its height by the factor k = 2, then all three heights will be in the correct ratio.Answer: B

Of the 190 bicycle stores in a certain region, 90 percent repair bicycles and 40 percent rent bicycles. If the integer n denotes the number of bicycle stores in the region that both repair and rent bicycles, which of the following indicates all possible values of n ?A. 38 ≤ n ≤ 76B. 57 ≤ n ≤ 76C. 57 ≤ n ≤ 171D. 76 ≤ n ≤ 95E. 76 ≤ n ≤ 171

B

Water flows into an empty swimming pool at a constant rate of 50 liters per minute. If the pool's total capacity is 120 cubic meters, approximately how many hours does it take until the pool is filled to 2/3 of its total capacity? (1 liter = 1,000 cubic centimeters)A) 7B) 13C) 27D) 40E) 53

C. 27

17. How many crayons are in a certain box?(1) If the crayons were evenly distributed among a group of 7 children, 3 crayons would be left over.(2) If the crayons were evenly distributed among a group of 4 children, 2 crayons would be left over.

Data Sufficiency

2. The average (arithmetic mean) of the 5 positive integers, u, w ,x, y, and z is 14, and u < w <x < y < z. If z is 26, what is the least possible value of the median of the 5 integers?(A) 3(B) 7(C) 8(D) 9(E) 10

For the unknown integers,u < w < x < y < 26andu + w + x + y + 26 = 14 × 5 = 70The median is the middle number in the list of 5 items in ascending order, so:median = xIf the sum of some variables is given, then we can minimize a certain variable by maximizing the others.The maximum value of y is 25. Clearly, w cannot be greater than "median - 1," and u cannot be greater than "median - 2."Of course, according to the given conditions, the median must be an integer.Let's now concentrate on the sum of the 5 integers:median - 2 + median - 1 + median + 25 + 26 = 703 × median = 22median = 7.33The median cannot be less than or equal to 7 because, in this case, the sum of the 5 integers would be less than 70.If the median, or x, is equal to 8, then w can be equal to 7, and u can be equal to the rest, or 70 - 26 - 25 - 8 - 7 = 4. Therefore, the least possible value of the median is 8. Answer: C

2. Bob expected to spend a total of $9.00 to buy a given amount of pasta salad at a fixed price per pound. However, the price of the salad was $0.20 more per pound than Bob had expected. Consequently, he spent $9.00 and bought 1212 pound less of the salad. How much did Bob spend per pound for the salad?A. $1.80B. $1.85C. $1.90D. $1.95E. $2.00

He expected to spend $9 to buy q pounds of salad at p dollars per pound:Total cost = p × q = $9However, things turned out differently for him:Total cost = (p + 0.2) × (q - 0.5) = $9Let's solve the system of equations for p.(p + 0.2) × (q - 0.5) = p × qpq + 0.2q - 0.5p - 0.1 = pq0.2q - 0.5p - 0.1 = 02q - 5p - 1 = 0q = (5p + 1)/2Now we can substitute the above expression for q in the first equation.p × (5p + 1)/2 = 95p^2 + p - 18 = 0(5p - 9)(p + 2) = 0If p + 2 = 0, then p = -2, which is an invalid case.If 5p - 9 = 0, then p = 9/5 = 1.8.Therefore, he paid 1.8 + 0.2 = $2 per pound for the salad.Answer: E

5. The nearest star outside our solar system is approximately 4 x 10^13 kilometers (km) from Earth and our moon is approximately 380,000 km from Earth. If these distances were scaled down so that the distance from Earth to our moon was represented by 1 centimeter, then which of the following is closest to the scaled down distance, in kilometers, from Earth to the nearest star outside our solar system?A. 10B. 100C. 1,000D. 100,000E. 1,000,000

If we denote the scaled down distance from Earth to Moon by 1 cm', then we have the following unit conversion equation: 1 cm' = 3.8 × 10⁵ km In addition, we need to consider the following unit conversion equations as well:1 m' = 100 cm'1 km' = 1,000 m' Now, we simply multiply 4 × 10¹³ km by the corresponding unit conversion factors until all unnecessary units of measurement cancel out. (4 × 10¹³ km)(1 cm'/3.8 × 10⁵ km)(1 m'/10² cm')(1 km'/10³ m') == 4/3.8 × 10³ km' ≈ 1 × 10³ km' = 1,000 km' Answer: C_________________

9. At a recent sale, Harue bought various numbers of 5 types of school supplies - markers, pens, pencils, erasers, and notebooks - each advertised with a different pricing strategy. Harue bought 4 markers for the price of 3, 3 pens for the price of 2, 5 pencils for the price of 3, 2 erasers for the price of 1, and 5 notebooks for the price of 2. One of the 5 types of school supplies was advertised as "Buy one, get one at 50% off." Which type?A. MarkersB. PensC. PencilsD. ErasersE. Notebooks

If x is the regular price of an item, then "Buy one, get one at 50% off" means "Pay a total of x + 0.5x = 1.5x if you buy two of these items."Let's check the types of supplies he bought.If the advertised phrase applied to markers, then for 4 markers he would have to pay (x + 0.5x) + (x + 0.5x) = 3x instead of 4x. In other words, he could buy 4 markers for the price of 3. Since he actually bought 4 markers for the price of 3, we know the markers were advertised with the phrase.Answer: A

3. For the rental of a certain type of car, rental agency R charges a fee of $30 per day plus a fee of $0.20 for each mile traveled in excess of 100 miles per day. For the rental of the same type of car, rental agency S charges a fee of $65 per day with free unlimited mileage. If a car of this type is to be rented for 3 days and will be driven the same number of miles each day, for what total number of miles will the cost of renting the car from rental agency R be the same as the cost of renting the car from rental agency S ?A) 352B) 405C) 525D) 750E) 825

Let us work out the rent by each agency by taking y as the number of miles per day.1) Rental Agency R: 30+0.20(y-100) per day2) Rental Agency S: 65 per day.If both are equal = 30+0.20(y−100)=65.......15(y−100)=35.......y−100=175.......y=27530+0.20(y−100)=65.......15(y−100)=35.......y−100=175.......y=275 Since we are looking for miles in 3 days => 3*275 = $825E

20. Microsaddes: 3. The passage most strongly suggests that frogs have which of the following?

Then, it says the following about frogs: Some animals, such as frogs, are completely unable to see stationary objects, but can easily see objects in motion. The reason humans see stationary objects better than do frogs may be that human eyes create their own motion, prompting visual neurons to keep firing. The motion that human eyes create to see stationary objects is understood to be microsaccades. So, if the reason humans see stationary objects better than do frogs may be that humans create microsaccades, then the passage is suggesting that frogs have eyes that do not create microsaccades.Keep.

11. In a survey on sales of soft drinks, 65 percent of the surveyed customers said that they buy brand A regularly, 60 percent said that they buy brand B regularly, and 32 percent said that they do not usually buy either of the two brands. What percent of the surveyed customers said that they buy both brands A and B regularly?A. 37B. 54C. 57D. 59E. 61

To solve this problem, we can use a formula for 2 overlapping sets: Total = #A + #B - #Both + #Neither The formula works well even if we have percentage data only.100% = 65% + 60% - Both + 32%Both = 57% Answer: C

10. A store sold 60 percent of the hats from a shipment of hats at a selling price that was 50 percent greater than the store's cost for each hat. Then the store reduced the selling price by 66 2/3 percent and sold 70 percent of the remaining hats at the reduced selling price. If the store did not sell any other hats form the shipment, then the store's gross profit from the sale of the hats from the shipment was what percent of the store's cost for the hats from the shipment?A) 1%B) 4%C) 9%D) 13%E) 25%

Total cost = q × p = qpThe total revenue from the sale of 60 percent of the hats:Total revenue₁ = 0.6q × 1.5p = 0.9qp(Note: "50 percent greater" corresponds to a factor of 1.5.)The total revenue from the sale of 70 percent of the remaining 40 percent of the hats:Total revenue₂ = (0.7)(0.4)q × (1/3)(1.5)p = 0.14qp(Note: "66 2/3 percent decrease" corresponds to a factor of 0.333, or 1/3.)Total profit = Total revenue₁ + Total revenue₂ - Total costTotal profit = 0.9qp + 0.14qp - qp = 0.04qpTherefore, the percentage in question is:Percentage = Total profit/Total cost = 0.04qp/qp = 0.04 = 4% Answer: B

16. Which of the following is a value of x for which x^−9-x^−7>0? A. -2B. -1C. −12−12D. 1E. 2

Using the exponent rules, we have:1/x^9 - 1/x^7 > 0We see that x cannot be equal to zero.If x > 0, then:1 - x^9/x^7 > 01 - x^2 > 01 > x^2|x| < 1 => -1 < x < 1So, in this case, it must be true that 0 < x < 1.If x < 0, then:1 - x^9/x^7 < 0|x| > 1 => x > 1 OR x < -1So, in this case, it must be true that x < -1.Therefore, x < -1 OR 0 < x < 1. Answer: A

Given that 1 acre and 4,840 square yards are equal areas, 1 rod and 5.5 yards are equal lengths, and 1 furlong and 40 rods are equal lengths, which of the following is closest to an area, in square furlongs, equal to 1 acre?A. 0.05B. 0.1C. 1D. 10E. 22

We need to determine the area in square furlongs.To quickly solve such a unit conversion problem, we can simply multiply the corresponding unit conversion factors and the value to convert until all unnecessary units cancel out:(1 fur²/40² rod²)(1 rod²/5.5² yd²)(4840 yd²/1 ac)(1 ac) =4840/[(40²)(5.5²)] fur²Since the answer choices are of different magnitudes, we can approximate the correct answer:≈ 5000/(40 × 40 × 5 × 5) = 2/16 = 1/8 = 0.125 ≈ 0.1 fur²Answer: B

1. If a=2‾√—1�=2—1 and b = 1, which of the following is equal to [a2+b(b+2a)]+[b2+a(a+2b)][�2+�(�+2�)]+[�2+�(�+2�)] ?A. 2B. 4C. 22‾√22D. 2+22‾√2+22E. 4+22‾√

[a2�2 + b(b + 2a)] + [b2�2 + a(a + 2b)](a2+b2+2ab)+(b2+a2+2ab)(�2+�2+2��)+(�2+�2+2��)2(a+b)22(�+�)2Let's substitute the value of a and b2(2‾√—1+1)22(2—1+1)22(2‾√)22(2)22∗2=42∗2=4Option B

A certain assistant professor in the Art History department at University X is being evaluated for promotion. One of the requirements is a performance score of at least 4.0. The performance score is the weighted average of 3 component scores: one for research, one for teaching, and one for service, with the scores for research and teaching each weighted 40% and the score for service weighted 20%. Each component score is between 0.0 and 5.0, inclusive.Consistent with the given information, select for Minimum service score the least possible score the professor can receive for service and still achieve a performance score of at least 4.0, and select for Minimum research score the least possible score the professor can receive for research and still achieve a performance score of at least 4.0. Make only two selections, one in each column.

https://youtu.be/OZLsNRPjbzs

5. If x = -1 and if n is the sum of the first 404 prime numbers, then x+xN+xN+1+xN+2�+��+��+1+��+2 =A. -4B. -2C. 0D. 2E. 4

The first prime number is 2, which is the only even prime number.N = 2 + the sum of 403 odd prime numbers = even + odd = oddThe expression in question can be written as:(-1) + (-1)^odd+(-1)^even+(-1)^odd = (-1) + (-1) + 1 + (-1) = 1 - 3 = -2Answer: B

15. A promotional video that lasts w minutes has 3 segments which last x, y, and z minutes, respectively. A celebrity host narrates 1/3 of the first segment, 1/2 of the second segment, and 1/2 of the third segment. If 3x = 3y = z, what fraction of the w-minute video does the celebrity host narrate?A. 1/4B. 4/15C. 3/7D. 4/9E. 7/15

The fraction of the whole video narrated by the celebrity can be expressed as a weighted average of the narrated fractions of the components:[x(1/3) + y(1/2) + z(1/2)]/(x + y + z)Since x = z/3 and y = z/3, we have:[(z/3)(1/3) + (z/3)(1/2) + z(1/2)]/(z/3 + z/3 + z) =(1/9 + 1/6 + 1/2)/(1/3 + 1/3 + 1) =(14/18)/(5/3) = 7/15Answer: E

8. One year ago a window washing service charged $100 for setup and an additional $30 per hour for on-site washing. This year the company charges $20 for setup and an additional $50 per hour for on-site washing. Which of the following is equivalent to the percentage change from last year to this year that the company charges for setup and x hours of on-site washing?A. 100(3x+102x−8)%100(3�+102�−8)%B. 200(x−43x+10)%200(�−43�+10)%C. 200(x−45x+2)%200(�−45�+2)%D. 200(4−x3x+10)%200(4−�3�+10)%E. 200(4−x5x+2)%

percent change = [(new - old)/old] × 100%new amount charged = 20 + 50xold amount charged = 100 + 30xpercent change = [(20 + 50x - 100 - 30x)/(100 + 30x)] × 100% =[(20x - 80)/(30x + 100)] × 100% =100[(2x - 8)/(3x + 10)]% =200[(x - 4)/(3x + 10)]% Answer: B

13. For each positive integer k, let ak= 7k. Which of the following is the greatest value of n such that 10^n divides (a1)(a2)(a3)...(a28)?A. 7B. 6C. 5D. 4E. 3

y = (a₁)(a₂)...(a₂₈) = (7×1)(7×2)...(7×28)y = (7^28)(28!)We need to find the greatest n such that:y/10^n = inty/[(2^n)(5^n)] = intThe expression above is an integer if n is not greater than the total number of 2s in the prime factored form of y and if n is not greater than the total number of 5s in the prime factored form of y.Since in the prime factored form of y, there are fewer 5s than 2s, we need to concentrate on the total number of 5s, which we can quickly determine with the following technique:28/5 = 5 (ignore the remainder)5/5 = 1The total number of 5s is 5 + 1 = 6, so we have:n ≤ 6Answer: B(Note: We can ignore 7^28 because it doesn't contain neither 2s nor 5s.)

17. Of the 400 employees in a certain office, 260 have been given a watch and 80 have been give a cell phone. If the number of the employees have been given both a watch and a cell phone is 1/2 the number who have been given neither a watch nor a cell phone. How many employees have been give a watch but not a cell phone?A. 90B. 170C. 180D. 200E. 220

#W + #C - #W&C + Neither = Total260 + 80 - (1/2)Neither + Neither = 400(1/2)Neither = 60Neither = 120#W&C = (1/2)120 = 60#W&NC = #W - #W&C = 260 - 60 = 200Therefore, 200 employees have been given a watch but not a cell phone.Answer: D

4. Indeed, to remarkably high precision, the human eye is most sensitive to the exact frequency in the yellow part of the spectrum at which the Sun is the brightest. 3. Which of the following most accurately describes the purpose of the highlighted sentence in relation to the passage as a whole?A. To indicate the author's surprise at the manner in which human eyes have developed in relation to the visible spectrum of lightB. To illustrate that the correspondence between human eyes' sensitivity and the frequencies of light comprising the visible spectrum is not merely coincidentalC. To assert that human eyes are more finely tuned to a particular part of the visible spectrum of light than are those of some other organisms on EarthD. To explain why the gases that comprise Earth's atmosphere do not absorb the frequencies of light that the Sun emits most abundantlyE. To support the claim that the Sun is an average star w

1. The main purpose of the passage is to We can bring the main purpose of the passage into focus by considering the important points and structure of the passage. The passage begins by presenting a general fact about light: "Light exists on a spectrum of frequencies extending from gamma rays at the highest frequencies to radio waves at the lowest." It then uses the contrast marker "though" to present a contrasting point about human eyes: "human eyes are sensitive to only a narrow range of frequencies in the middle known as the visible spectrum." Then, it finishes the first paragraph by bringing up something that "one might wonder": "Given that there are so many frequencies of light, one might wonder why our eyes didn't evolve to be sensitive to more frequencies." Then, the second and third paragraphs explain why "we see the frequencies we do." Finally, the fourth paragraph explains why even "living beings on other planets" do not likely see at frequencies very different from those at which we see. With these important points in mind, we can go to the answer choices. A. present certain facts about the cosmos that indicate probable limits to the frequencies of light that living beings would be able to see As we discussed above, in the first paragraph, the passage brings up that "one might wonder why our eyes didn't evolve to be sensitive to more frequencies." Then, in the second, third and fourth paragraphs, it presents facts that explain why not only humans but even beings on other planets would be able to see light of only certain frequencies. So, as this choice says, the passage presents "certain facts about the cosmos that indicate probable limits to the frequencies of light that living beings would be able to see." Keep

7. Which of the following is equal to 16(48)716(48)7?A. 8^6B. 8^7C. 6(48)^6D. 8(48)^6E. 8(48)^7

A) 8^6 vs. (48/6)(48)^6 = 8(48)^6 [The right side is clearly greater.]B) 8^7 = 8(8^6) vs. 8(48)^6 [The right side is clearly greater.]C) 6(48)^6 vs. 8(48)^6 [The right side is clearly greater.]D) 8(48)^6 = 8(48)^6Since we have the correct answer, there's no need to check answer choice E.Answer: D

1. For the years 1972-2007, Total World Credit Market Debt (TWCMD), as measured in trillions of US dollars, is accurately modeled by the equation y=N•2k(t−1972)�=�•2�(�−1972), whose graph is given. Here, Nand k are positive constants and t denotes the year.From each drop-down menu, select the option that creates the most accurate statement based on the information provided.The constant N is approximately equal to ------- If the model continues to be accurate beyond 2007, the TWCMD will equal approximately double the 2007 value in the year

ANSWER: 3, 2016

14. In an experiment that lasted several weeks, volunteers were given either an assortment of snacks or only corn chips between meals. Beforehand, most volunteers predicted that they would be more satisfied with an assortment of snacks rather than just one kind of snack. But afterward, those who received only corn chips reported greater satisfaction. The researchers concluded from this that people tend to mistakenly believe that they prefer variety to monotony in their diets.Which of the following, if true, would most strengthen the researchers' reasoning?A. Before the experiment, most volunteers said that corn chips were their favorite snack among those offered.B. Other researchers have found that variety in diet is more satisfying than variety in other experiences.C. The volunteers were not informed beforehand that those who did not receive an assortment of snacks would receive only corn chips.D. The volunteers who

E. In a separate taste test, most people found the corn chips to be less appetizing than any other snack the volunteers received.This choice helps to confirm that people do not prefer variety to monotony and suggests that they prefer monotony to variety because it shows that, even though corn chips are less appetizing than other snacks, people STILL were more satisfied with the corn chips than with greater variety. So, something must have offset the fact that corn chips are less appetizing to make them more satisfied, and that offsetting factor appears to have been the monotony.Another way of looking at this choice is that it eliminates an alternative cause for the greater satisfaction of the people who received only corn chips by eliminating the possibility that they were more satisfied because corn chips are more appetizing.

Vicente: Off-road vehicles should be prohibited in our province's main wilderness park. In the past decade, the park's bird populations have declined substantially. This decline is probably attributable, at least in part, to off-road vehicle use. The number of off-road vehicles has been increasing steadily. Their use disrupts sensitive bird habitats.In Vicente's argument, the two portions in boldface play which of the following roles?

E. The first is a conclusion drawn in the argument but not the main conclusion; the second is a premise offered to support the first.This choice matches exactly what we have seen through analysis of the argument and our review of the other choices.The first boldfaced portion is a conclusion that is supported by the two statements that follow it, one of which is the second boldfaced portion.Then the first boldfaced portion supports the main conclusion of the argument, which is the first statement of the passage. So, it is the case that the first boldfaced portion is not the main conclusion.Thus, this choice accurately describes the roles of the two boldfaced portions of the passage.

6. If S is the sum of all the numbers of the form 1/n, where n is an integer from 33 to 64 inclusive, then S lies in which of the following intervals? (A) 0 < S < 1/64(B) 1/64 < S < 1/32(C) 1/32 < S < 1/2(D) 1/2 < S < 1(E) 1 < S < 2

S = 1/33 + 1/34 + ... + 1/64We see that S is the sum of 64 - 33 + 1 = 32 different fractions. Of these fractions, 1/64 is the smallest, and 1/33 is the greatest. Therefore, 32(1/64) < S < 32(1/33)32/64 < S < 32/33 < 33/331/2 < S <1 Answer: D

A committee recently held a planning meeting for a craft fair. The committee decided that the fair would occur on a Tuesday and that a public discussion about the fair would be held sometime after, also on a Tuesday.In the table, select for Fair a number of days between the planning meeting and the fair and select for Discussion a number of days between the planning meeting and the public discussion that would be jointly consistent with the given information, Make only two selections, one in each column.

Since both the fair and the discussion will be held on a Tuesday, there will be one or more weeks between the fair and the discussion.Thus, since a week is 7 days long, the difference between the number of days between the planning meeting and the fair and the number of days between the planning meeting and the discussion must be a multiple of 7.We can narrow down our choices by noticing that, since there will be fewer days between the planning meeting and the fair than between the planning meeting and the discussion, the lowest number among the choices could be selected only for the first column, and the highest number among the choices could be selected only for the second column.Then, using that constraint to our advantage, we simply find two numbers such that the one in the second column is greater than the one in the first column by a multiple of 7.We can methodically subtract each lower number from each higher number to find a difference that is a multiple of 7.

19. The Chabberton Post-Gazette reported that the overall volume of retail sales in Chabberton was lower last year than it was the year before. The Post-Gazette based that conclusion on a survey of all retail stores that were in business in Chabberton throughout both of those years: these stores, taken together, had a smaller sales volume last year than the year before.Which of the following, if true, casts the most serious doubt on the Post-Gazette's conclusion?A. Last year several new retail stores opened in Chabberton, offering high quality merchandise at competitive prices.B. Many Chabberton residents do most of their shopping at stores in other towns in the vicinity of Chabberton.C. Most of the Chabberton stores that the survey covered advertise regularly in the Chabberton Post-Gazette.D. A separate survey of manufacturing businesses in Chabberton shows that they did a greater volume of business last year than t

a survey of all retail stores that were in business in Chabberton throughout both of those years: these stores, taken together, had a smaller sales volume last year than the year before This information seems to support the conclusion, but one thing we may notice is that the sample used to support the conclusion is limited. It includes only stores "in business in Chabberton throughout both of those years." What about other stores? Let's now go to the answer choices. A. Last year several new retail stores opened in Chabberton, offering high quality merchandise at competitive prices. This choice seems to cast doubt on the conclusion that "the overall volume of retail sales in Chabberton was lower last year than it was the year before." After all, while stores that were "in business in Chabberton throughout both of those years" may have seen declines in sales, the sales at these new stores could have added to "overall sales." So, given what this choice says, "overall volume of sales" last year may have been similar to or greater than, rather than smaller than, the volume the year before. Thus, this choice provides a clear reason to doubt the conclusion. Keep this choice.

19. In a set of 5 measurements with an average (arithmetic mean) of 60, one of the measurements is found to be incorrect. If this measurement is replaced by its correct value of 80, then the average of the resulting set is 70. What is the value of the incorrect measurement?A. 10B. 20C. 25D. 30E. 50

average = sum of terms/number of termsnumber of terms = 5incorrect average = 60sum of terms with one incorrect measurement = 5(60) = 300If x is the incorrect measurement, we have:sum of terms with correct measurements = 300 - x + 80 = 380 - xSince the correct average is 70, we have:(380 - x)/5 = 70380 - x = 350x = 30Answer: D