1 of 20 5.0 Points Decide which of the described variables is/are likely to have a normal or near-normal distribution. a) The heights of corn stalks in one row of corn that is half a mile long b) The numbers of viewers of each of the channels from 202 to 550 on Direct TV at 7:00 PM CDT on the third Thursday of November 2012 (349 data values) A. a B. b C. a and b Question 3 of 20 5.0 Points The diameters of bolts produced by a certain machine are normally distributed with a mean of 0.25 inches and a standard deviation of 0.01 inches. What percentage of bolts will have a diameter greater than 0.24 inches? A. 79.13% B. 82.46% C. 84.13% D. 84.46% Question 5 of 20 5.0 Points If light bulbs have lives that are normally distributed with a mean of 2500 hours and a standard deviation of 500 hours, approximately what percentage of light bulbs has a life of more than 3000 hours? A. About 84% B. About 68% C. About 32% D. About 16% Question 7 of 20 5.0 Points The systolic blood pressure of 18-year-old women is normally distributed with a mean of 120 mm Hg and a standard deviation of 12 mm Hg. What percentage of 18-year-old women have a systolic blood pressure that is within 3 standard deviations of the mean on either side? Apply the 68-95-99.7 rule to this question. A. 68% B. 95% C. 100% D. 99.7% Question 8 of 20 5.0 Points The lifetimes of light bulbs of a particular type are normally distributed with a mean of 270 hours and a standard deviation of 11 hours. What percentage of the bulbs has lifetimes that lie within 2 standard deviations of the mean on either side? Apply the 68-95-99.7 rule to this questions. A. 68% B. 1005 C. 99.7% D. 95% Question 11 of 20 5.0 Points Decide which of the described variables likely have a normal or nearnormal distribution. a) The amount of change held by a teacher at the end of each day for a year b) The amount of pocket money held by each student at a mid-sized liberal arts college at a given time c) The number of heads that show when two coins are tossed A. a B. b C. c D. None Question 12 of 20 5.0 Points The annual precipitation for one city is normally distributed with a mean of 28 inches and a standard deviation of 3.4 inches. Fill in the blanks. In 95% of the years, the precipitation in this city is between __________ and __________ inches. Apply the 68-95-99.7 rule to this question. A. 21.2, 34.8 B. 21.2, 34.6 C. 22.4, 34.6 D. 22.4, 34.8 Question 13 of 20 5.0 Points A math teacher gives two different tests to measure students' aptitude for math. Scores on the first test are normally distributed with a mean of 24 and a standard deviation of 4.5. Scores on the second test are normally distributed with a mean of 70 and a standard deviation of 11.3. Assume that the two tests use different scales to measure the same aptitude. If a student scores 29 on the first test, what would be his equivalent score on the second test? (That is, find the score that would put him in the same percentile.) A. 87 B. 85 C. 86 D. 83 Question 14 of 20 5.0 Points The volumes of soda in quart soda bottles are normally distributed with a mean of 32.3 oz and a standard deviation of 1.2 oz. What is the probability that the volume of soda in a randomly selected bottle will be less than 32 oz? A. 0.5012 B. 0.5010 C. 0.4015 D. 0.4013 Question 15 of 20 5.0 Points The mean score on the exit examination for an urban high school is 63 with a standard deviation of 9. What is the standard deviation of the distribution of sample means with a sample size of 9? A. 2 B. 3 C. 4 D. 4.1 Question 16 of 20 5.0 Points The area under the standard normal curve between 1 and 2 is equal to 0.1359. Scores on a particular aptitude test are normally distributed with a mean of 100 and a standard deviation of 10. Which of the following are equal to 13.59%? a) The percentage of scores between 120 and 130 b) The percentage of scores between 110 and 120 c) The percentage of scores between 80 and 90 d) The percentage of scores between 90 and 120 A. b B. b, c C. d D. a, b Question 17 of 20 5.0 Points The annual precipitation for one city is normally distributed with a mean of 72 inches and a standard deviation of 3.5 inches. Fill in the blanks. In 99.7% of the years, the precipitation in this city is between __________ and __________ inches. Apply the 68-95-99.7 rule to this questions. A. 61.5, 82. 5 B. 82.5, 61.5 C. 61.5, 85.5 D. 63.5, 82.5 Question 18 of 20 5.0 Points The scores on a certain test are normally distributed with a mean score of 58 and a standard deviation of 4. What is the likelihood that a sample of 90 students will have a mean score of at least 58.4216? A. 0.8413 B. 0.3413 C. 0.3174 D. 0.1587 Question 19 of 20 5.0 Points The lifetimes of projector bulbs of a particular type are normally distributed with a mean of 470 hours and a standard deviation of 15 hours. What percentage of the bulbs has lifetimes that lie within 2 standard deviations of the mean on either side? Apply the 68-95-99.7 rule to this question. A. 68% B. 99.7% C. 95% D. 100% Question 20 of 20 5.0 Points If light bulbs have lives that are normally distributed with a mean of 2500 hours and a standard deviation of 500 hours, use the 68-95-99.7 rule to approximate the percentage of light bulbs having a life between 2000 hours and 3500 hours? A. About 13.5% B. About 50% C. About 68% D. About 81.5%