Mrs. Owen Midterm Exam

The same 1200 tomatoes from above have a mean weight of 143 grams and a standard deviation of 35 grams. If the weights are Normally distributed, approximately how many tomatoes weight between 73 grams and 178 grams?

(d) 978

Forty pound bags of bird seed do not have exactly 40 pounds of seed, but the weight of seed is approximately Normally distributed with a mean of 40 pounds and a standard deviation of 0.25 pounds. Which if the following is the best estimate of the 90th percentile for the weight of bags of seed?

(a) 40.3 pounds

Which of the following is closest to the 61st percentile of a standard Normal distribution?

(d) z=0.7291

A special 20-sided die is constructed so that each face has either a 1,2,3, or 4 on it. The table below gives the probability of each value (with one value missing). Which of the following is the probability of rolling an odd number?

(e) 0.6

The scatterplot at right shows the relationship between carbohydrates and protein in one-cup servings of 15 different varieties of beans.

(a) The correlation would be closer to 1, because the remaining data would have a stronger positive relationship.

One hundred people work at Lagtime Internet Services. Suppose after a particularly successful year, the president of the company decided to double his own salary and not change anyone else's. Assuming the president makes more than anyone else, which of the following statements about changes un measures of center and spread is true?

(a) The mean and standard deviation will increase, but the median interquartile range will stay home.

Which one of the two-way tables below conveys the same information?

(b)

All of the following small data set have a mean of 5. Which one has the lowest standard deviation?

(b) 1 3 5 5 5 7 9

You randomly select one truck owner. What is the probability that he owns a Chevy, given that he has four wheel drive?

(b) 32/80

Which of the following is the best description of a sample of size n from a population of size N.

(b) Any method of sampling in which every group of individuals of size n is equally likely to be selected.

What is the principile purpose of control in a randomized comparative experiment?

(b) Isolating the effect of the treatment variable by keeping all the other variables the same in the treatment groups

An airline has 10 daily flights from Philadelphia to Denver. To assess customer satisfaction, a random sample of 15 passengers from each flight on a single day are asked to fill out a survey about their experience on the flight. What type of sample is this?

(b) Stratified random sample

A biology teacher has just finished grading a quiz for a class of 26 and has calculated measures of center and spread on the scores. While writing the grades on the quizzes, he realizes he made a mistake, and the highest grade should be 10 points higher. Which one of the following sets of measurements will he have to recalculate?

(b) The mean and standard deviation

At right are box plots describing the distribution of prices paid for homes in two suburbs of Columbus, Ohio over a single 30-day period in 2012. Which of the following statements is supported by the information in this graph?

(b) The median house price in Dublin is higher than the 75th percentile of house price in Westerville.

Which of the following is not true about the standard deviation?

(c) If the units for the data are in inches, standard deviation is in square inches.

Which of the following statements about standard deviation is true?

(c) Standard deviation is always a non-negative number

The weights of adult male Labrador Retrievers are approximately Normally distributed with a mean of 87 pounds and a standard deviation of 8 pounds. Which of the following statement is true?

(c) The proportion of adult male Labrador Retrievers that weigh less than 80 pounds is approximately equal to the proportion that weigh more 94 pounds

At right is a stemplot of the weights of 18 adult Maine Coon Cats. Which one of the following statements must be true about this distribution?

(c) The standard score for a 14-pound cat is negative.

You randomly select one truck owner. Which of the following is true about the events "owner has a Chevy" and "owner's truck has four wheel drive"?

(c) These two events are not mutually exclusive, but they are independent.

For the track coach's study described in the previous exercise, which of the following best describes a conclusion that can be dran?

(c) We can determine wether the new training program improves race times more than the standard program for the distance runners in this study

The customer service department of an online store keeps track of the length of time customers wait on hold for a representative. The mean wait time is 5 minutes and the standard deviation is 2.3 minutes. Suppose the company wants to change the variable from minutes to seconds exceeding a target time of 120 seconds. That is, if X is wait time on minutes, the new variable is Y= 60X-120. Which of the following are the mean and standard deviation of Y?

(c) mean= 180; Standard deviation = 138

Gabriel has determined that if he gets to the bus stop by 7:30 am, there is a 0.15 probability that he misses the bus. If he is at the bus stop three consecutive days at 7:30, what is the approximate probability that he catches the bus all three days?

(d) 0.614

The cumulative relative frequency graph at right shows the distribution of lifespans for 39 U.S. presidents. Which of the following is closest to the 70th percentile of this distribution?

(d) 77 years

A group of 125 pick-up truck owners were asked what brand truck they owned and wether it had four-wheel drive. The results are given in the two-way table below. You randomly select one truck owner. What probability that he owns a Dodge or has four wheel drive?

(d) 90/125

If you flip three coins, the probability of getting three heads is 0.215. Which of the following statements follow from this?

(d) If you flip three coins 5000 times, the percentage of time you get three heads will be very close 12.5%.

The bar graph at right shows the distribution of religious affiliation around the world. Which of the following statement best describes what is wrong with this graph?

(d) Starting the vertical scale at 5 distorts the relative frequency of the religions

Some studies of the relationship between car color and frequency of accidents have found that red cars are more likely to be in accidents than black cars, despite how visible they are. Some experts warn that we should not conclude that red cars are less safe than black cars, because of possible confounding. Which of the following best describes what this means?

(d) Studies of this type are all observational, and it is not possible to separate the effect of car color from the type of people who choose to drive red cars.

The time it takes people to finish a certain kind of puzzle is strongly skewed right. Which of the following statements is true about the mean and median of this distribution?

(d) The mean will be greater than the median.

A political action committee sends out a questionnaire to randomly-selected mailing addresses, asking people to rate the importance of a variety of economic and social issues facing the country. At the end of the questionnaire is an (optional) invitation to donate money to the organization. Which of the following statements about this survey is true?

(d) The survey results will overestimate support for this political action committee in the entire population because people more likely to respond if they are prepared to donate money.

The five-number summary for the weights (in grams) of 1200 tomatoes grown in a certain greenhouse was 90 113.5 140 161 236. How many tomatoes weighed less than 161 grams?

(e) 900

A track coach wants to test the effectiveness of a new training program for distance runners. He selects his two fastest runners and, using a coin flip, randomly chooses one to participate in the new program. The other will continue with the standard training regimen. He then picks the next two runners and randomly assigns one to each program. He repeats this process with all his runners, choosing the two fastest remaining each time. He then compares race times each group of two runners. What is the name for this kind of experimental design?

(e) Matched pairs design

A recent investigation of prices for five-year-old Toyota Camrys in Montgomery, Alabama, and New York, New York, revealed that the mean price in Montgomery was $13,200 with a standard deviation of $1000. In New York, the mean price was $12,800 with a standard deviation $1800. Which of the following statements is true?

The standard score for a car priced at $15,000 would be higher in Montgomery than in New York.