MATH 1280 - Review

σ = 3.02

Find the standard deviation, σ, for the binomial distribution which has the stated values of n and p. n = 38; p = 0.4 a. σ = 0.61 b. σ = 6.29 c. σ = 3.02 d. σ = 7.14

Continuous

Identify the given random variable as being discrete or continuous. What is the braking time of a car? a. Discrete b. Continuous

0.6321

If X ~ Exp (0.8), then P (x < μ) = — a. 0.3679 b. 0.4727 c. 0.6321 d. cannot be determined

0.6321

If X ~ Exp (0.8), then P (x < μ) = — a. 0.3679 b. 0.4727 c. 0.6321 d. cannot be determined

Parameter

Imagine that the U.S. federal government had the means to survey all high school seniors in the United States concerning their plans for future education and employment and found that 50 percent were planning to attend a four-year college or university in the following year. What is this 50 percent is an example of? a. Parameter b. Statistic c. Variable d. Data

The mode

In a left-skewed distribution, which is greater? a. The mean b. The median c. The mode

The mean

In a right-skewed distribution, which is greater? a. The mean b. The median c. The mode

0.2963

In one town, the number of burglaries in a week has a Poisson distribution with a mean of 1.9. Find the probability that in a randomly selected week the number of burglaries is at least three. a. 0.1710 b. 0.1253 c. 0.8290 d. 0.7037 e. 0.2963

8.25

On any given day, approximately 37.5 percent of the cars parked in the De Anza parking garage are parked crookedly. We randomly survey 22 cars. We are interested in the number of cars that are parked crookedly. For every 22 cars, how many would you expect to be parked crookedly, on average? a. 8.25 b. 11 c. 18 d. 7.5

0.2870

On any given day, approximately 37.5 percent of the cars parked in the De Anza parking garage are parked crookedly. We randomly survey 22 cars. We are interested in the number of cars that are parked crookedly. What is the probability that at least 10 of the 22 cars are parked crookedly? a. 0.1263 b. 0.1607 c. 0.2870 d. 0.8393

30/52

One hundred eighteen students were asked what type of color their bedrooms were painted: light colors, dark colors, or vibrant colors. The results were tabulated according to gender. Find the probability that a randomly chosen student is male given the student's bedroom is painted with dark colors. a. 30/118 b. 30/48 c. 22/118 d. 30/52

68/118

One hundred eighteen students were asked what type of color their bedrooms were painted: light colors, dark colors, or vibrant colors. The results were tabulated according to gender. Find the probability that a randomly chosen student is male or has a bedroom painted with light colors. a. 10/118 b. 68/118 c. 48/118 d. 10/48

1/4

Richard's Furniture Company delivers furniture from 10 a.m. to 2 p.m. continuously and uniformly. We are interested in how long (in hours) past the 10 a.m. start time that individuals wait for their delivery. Suppose that it is now past noon on a delivery day. The probability that a person must wait at least one and a half more hours is: a. 1/4 b. 1/2 c. 3/4 d. 3/8

two hours

Richard's Furniture Company delivers furniture from 10 a.m. to 2 p.m. continuously and uniformly. We are interested in how long (in hours) past the 10 a.m. start time that individuals wait for their delivery. The average wait time is: a. one hour b. two hours c. two and a half hours d. four hours

U (0, 4)

Richard's Furniture Company delivers furniture from 10 a.m. to 2 p.m. continuously and uniformly. We are interested in how long (in hours) past the 10 a.m. start time that individuals wait for their delivery. Χ ~ _____ (_____, _____) a. U (0, 4) b. U (10, 2) c. Eχp (2) d. N (2, 1)

cluster sampling.

Sara, a statistics student, wanted to determine the mean number of books that college professors have in their office. She randomly selected two buildings on campus and asked each professor in the selected buildings how many books are in his or her office. Sara surveyed 25 professors. The type of sampling selected is: a. simple random sampling. b. systematic sampling. c. cluster sampling. d. stratified sampling.

Statistic

The U.S. federal government conducts a survey of high school seniors concerning their plans for future education and employment. One question asks whether they are planning to attend a four-year college or university in the following year. Fifty percent answer yes to this question. What is that 50 percent? a. Parameter b. Statistic c. Variable d. Data

0.0142

The cost of unleaded gasoline in the Bay Area once followed an unknown distribution with a mean of $4.59 and a standard deviation of $0.10. Sixteen gas stations from the Bay Area are randomly chosen. We are interested in the average cost of gasoline for the 16 gas stations. Find the probability that the average price for 30 gas stations is less than $4.55. a. 0.6554 b. 0.3446 c. 0.0142 d. 0.9858 e. 0

almost zero

The cost of unleaded gasoline in the Bay Area once followed an unknown distribution with a mean of $4.59 and a standard deviation of $0.10. Sixteen gas stations from the Bay Area are randomly chosen. We are interested in the average cost of gasoline for the 16 gas stations. What's the approximate probability that the average price for 16 gas stations is more than $4.69? a. almost zero b. 0.1587 c. 0.0943 d. unknown

Yes

The length of time it takes to find a parking space at 9 a.m. follows a normal distribution with a mean of five minutes and a standard deviation of two minutes. Based on the given information and numerically justified, would you be surprised if it took less than one minute to find a parking space? a. Yes b. No c. Unable to determine

0.0668

The length of time it takes to find a parking space at 9 a.m. follows a normal distribution with a mean of five minutes and a standard deviation of two minutes. Find the probability that it takes at least eight minutes to find a parking space. a. 0.0001 b. 0.9270 c. 0.1862 d. 0.0668

II only

The length of time it takes to find a parking space at 9 a.m. follows a normal distribution with a mean of five minutes and a standard deviation of two minutes. If the mean is significantly greater than the standard deviation, which of the following statements is true? I. The data cannot follow the uniform distribution. II. The data cannot follow the exponential distribution. III. The data cannot follow the normal distribution. a. I only b. II only c. III only d. I, II, and III

3.95

The length of time it takes to find a parking space at 9 a.m. follows a normal distribution with a mean of five minutes and a standard deviation of two minutes. Seventy percent of the time, it takes more than how many minutes to find a parking space? a. 1.24 b. 2.41 c. 3.95 d. 6.05

0.8413

The lifetime of a computer circuit board is normally distributed with a mean of 2,500 hours and a standard deviation of 60 hours. What is the probability that a randomly chosen board will last at most 2,560 hours? a. 0.8413 b. 0.1587 c. 0.3461 d. 0.6539

Cluster

The manager of a department store decides to measure employee satisfaction by selecting four departments at random and conducting interviews with all the employees in those four departments. What type of survey design is this? a. Cluster b. Stratified c. Simple random d. Systematic

7.99

The patient recovery time from a particular surgical procedure is normally distributed with a mean of 5.3 days and a standard deviation of 2.1 days. The 90th percentile for recovery times is? a. 8.89 b. 7.07 c. 7.99 d. 4.32

5.3

The patient recovery time from a particular surgical procedure is normally distributed with a mean of 5.3 days and a standard deviation of 2.1 days. What is the median recovery time? a. 2.7 b. 5.3 c. 7.4 d. 2.1

0.9420

The patient recovery time from a particular surgical procedure is normally distributed with a mean of 5.3 days and a standard deviation of 2.1 days. What is the probability of spending more than two days in recovery? a. 0.0580 b. 0.8447 c. 0.0553 d. 0.9420

2.2

The patient recovery time from a particular surgical procedure is normally distributed with a mean of 5.3 days and a standard deviation of 2.1 days. What is the z-score for a patient who takes 10 days to recover? a. 1.5 b. 0.2 c. 2.2 d. 7.3

0.2442

The probability that a car will have a flat tire while driving through a certain tunnel is 0.00004. Use the Poisson distribution to approximate the probability that among 7000 cars passing through this tunnel, at least one will have a flat tire. a. 0.2442 b. 0.3126 c. 0.7558 d. 0.7884 e. 0.2116

40.3

The time to wait for a particular rural bus is distributed uniformly from zero to 75 minutes. One hundred riders are randomly sampled to learn how long they waited. The 90th percentile sample average wait time (in minutes) for a sample of 100 riders is: a. 315.0 b. 40.3 c. 38.5 d. 65.2

Yes

The time to wait for a particular rural bus is distributed uniformly from zero to 75 minutes. One hundred riders are randomly sampled to learn how long they waited. Would you be surprised, based on numerical calculations, if the sample average wait time (in minutes) for 100 riders was less than 30 minutes? a. yes b. no c. There is not enough information.

2.78

We are interested in the number of times a teenager must be reminded to do his or her chores each week. A survey of 40 mothers was conducted. The table below shows the results of the survey. Find the expected number of times a teenager is reminded to do his or her chores. a. 15 b. 2.78 c. 1.0 d. 3.13

8/40

We are interested in the number of times a teenager must be reminded to do his or her chores each week. A survey of 40 mothers was conducted. The table below shows the results of the survey. Find the probability that a teenager is reminded two times. a. 8 b. 8/40 c. 6/40 d. 2

Quantitative-discrete

What kind of data is the amount of money spend in a grocery store? a. Qualitative b. Quantitative-continuous c. Quantitative-discrete

Median

Which measure of the center of data would a clothing store use when placing orders for the typical middle customer? a. Mean b. Median c. Mode d. IQR

The curve is skewed to the right.

Which of the following is NOT true about the distribution for averages? a. The mean, median, and mode are equal. b. The area under the curve is 1. c. The curve never touches the x-axis. d. The curve is skewed to the right.

The curve is skewed to the right.

Which of the following is NOT true about the theoretical distribution of sums? a. The mean, median, and mode are equal. b. The area under the curve is one. c. The curve never touches the x-axis. d. The curve is skewed to the right.

Stratified

A community college offers classes six days a week: Monday through Saturday. Maria conducted a study of the students in her classes to determine how many days per week the students who are in her classes come to campus for classes. In each of her five classes she randomly selected 10 students and asked them how many days they come to campus for classes. Each of her classes are the same size. The results of her survey are summarized in the table below: Combined with convenience sampling, what other sampling technique did Maria use? a. Simple random b. Systematic c. Cluster d. Stratified

25

A community college offers classes six days a week: Monday through Saturday. Maria conducted a study of the students in her classes to determine how many days per week the students who are in her classes come to campus for classes. In each of her five classes she randomly selected 10 students and asked them how many days they come to campus for classes. Each of her classes are the same size. The results of her survey are summarized in the table below: How many students come to campus for classes four days a week? a. 49 b. 25 c. 30 d. 13

4

A community college offers classes six days a week: Monday through Saturday. Maria conducted a study of the students in her classes to determine how many days per week the students who are in her classes come to campus for classes. In each of her five classes she randomly selected 10 students and asked them how many days they come to campus for classes. Each of her classes are the same size. The results of her survey are summarized in the table below: What is the 60th percentile for this data? a. 2 b. 3 c. 4 d. 5

5.8

A community college offers classes six days a week: Monday through Saturday. Maria conducted a study of the students in her classes to determine how many days per week the students who are in her classes come to campus for classes. In each of her five classes she randomly selected 10 students and asked them how many days they come to campus for classes. Each of her classes are the same size. The results of her survey are summarized in the table below: X ~ U (4, 10). Find the 30th percentile. a. 0.3000 b. 3 c. 5.8 d. 6.1

Systematic

A health club is interested in knowing how many times a typical member uses the club in a week. They decide to ask every tenth customer on a specified day to complete a short survey, including information about how many times they have visited the club in the past week. What kind of a sampling design is this? a. Cluster b. Stratified c. Simple random d. Systematic

Quantitative-discrete

A health club is interested in knowing how many times a typical member uses the club in a week. They decide to ask every tenth customer on a specified day to complete a short survey, including information about how many times they have visited the club in the past week. What kind of data is number of visits per week? a. Qualitative b. Quantitative-continuous c. Quantitative-discrete

Statistic

A study finds that the mean amount spent in a grocery store per visit by customers in a sample is $12.84. This is an example of a: a. Population b. Sample c. Parameter d. Statistic e. Variable

μ = 473.2

Find the mean, μ, for the binomial distribution which has the stated values of n and p. n = 676; p = 0.7. a. μ = 474.9 b. μ = 473.2 c. μ = 474.5 d. μ = 471.7

3.5

According to a college survey, 22% of all students work full time. Find the mean for the number of students who work full time in samples of size 16. a. 3.5 b. 2.8 c. 4.0 d. 0.2

Independent

An experiment consists of tossing two, 12-sided dice (the numbers 1-12 are printed on the sides of each die). Let Event A = both dice show an even number. Let Event B = both dice show a number greater than eight. Events A and B are: a. Mutually exclusive b. Independent c. Mutually exclusive and independent d. Neither mutually exclusive nor independent

4/16

An experiment consists of tossing two, 12-sided dice (the numbers 1-12 are printed on the sides of each die). Let Event A = both dice show an even number. Let Event B = both dice show a number greater than eight. Find P(A|B) a. 2/4 b. 16/144 c. 4/16 d. 2/144