Unit 2 test

(2 points) Jorge’s score on Exam 1 in his statistics class was at the 64th percentile of the scores for all students. His score falls

• between the minimum and the first quartile.

• between the first quartile and the median.

• between the median and the third quartile.

• between the third quartile and the maximum.

• at the mean score for all students.

(2 points) Scores on the ACT college entrance exam follow a bell-shaped distribution with mean 18 and standard deviation 6. Wayne’s standardized score on the ACT was −0.7. What was Wayne’s actual ACT score?

• 4.2

• -4.2

• 13.8

• 17.3

• 22.2

(4 points) George has an average bowling score of 180 and bowls in a league where the average for all bowlers is 150 and the standard deviation is 20. Bill has an average bowling score of 190 and bowls in a league where the average is 160 and the standard deviation is 15. Who ranks higher in his own league, George or Bill?

• Bill, because his 190 is higher than George’s 180.

• Bill, because his standardized score is higher than George’s.

• Bill and George have the same rank in their leagues, because both are 30 pins above the mean.

• George, because his standardized score is higher than Bill’s.

• George, because the standard deviation of bowling scores is higher in his league.

(2 points) If every observation in a data set is multiplied by 10, the only one of the following that is not multiplied by 10 is

• the mean.

• the median.

• the IQR.

• the standard deviation.

• the variance.

(2 points) If 30 is added to every observation in a data set, the only one of the following that is not changed is

• the mean.

• the 75th percentile.

• the median.

• the standard deviation.

• the minimum.

(2 points) Which of the following is least likely to have a nearly Normal distribution?

• Heights of all female students taking STAT 001 at State Tech.

• IQ scores of all students taking STAT 001 at State Tech.

• SAT Math scores of all students taking STAT 001 at State Tech.

• Family incomes of all students taking STAT 001 at State Tech.

• All of (a)–(d) will be approximately Normal.

The weights of laboratory cockroaches follow a Normal distribution with mean 80 grams and standard deviation 2 grams. The figure below is the Normal curve for this distribution of weights.

Point C on this Normal curve corresponds to

• 84 grams.

• 82 grams.

• 78 grams.

• 76 grams.

• 74 grams.

The weights of laboratory cockroaches follow a Normal distribution with mean 80 grams and standard deviation 2 grams. The figure below is the Normal curve for this distribution of weights.

About what percent of the cockroaches have weights between 76 and 84 grams?

• 99.7%

• 95%

• 68%

• 47.5%

• 34%

The weights of laboratory cockroaches follow a Normal distribution with mean 80 grams and standard deviation 2 grams. The figure below is the Normal curve for this distribution of weights.

About what percent of the cockroaches have weights less than 78 grams?

• (a) 34%

• (b) 32%

• (c) 16%

• (d) 2.5%

• (e) none of these

(2 points) The proportion of observations from a standard Normal distribution with values less than 1.15 is

• 0.1251.

• 0.8531.

• 0.8749.

• 0.8944

• none of these.