# 15 42 53 7 9 12 14 28 47 a 291 b 166 c 178 d 158 exam

• 86

This preview shows page 38 - 43 out of 86 pages.

15, 42, 53, 7, 9, 12, 14, 28, 47 A. 29.1 B. 16.6 C. 17.8 D. 15.8
Exam 4_04 Return to Assessment List Part 1 of 1 - 95.0/ 100.0 Points Question 1 of 20 5.0/ 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?
B. 3 C. 4 D. 4.1 Question 2 of 20 5.0/ 5.0 Points A final exam in Math 160 has a mean of 73 with standard deviation 7.73. Assume that a random sample of 24 students is selected and the mean test score of the sample is computed. What percentage of sample means are less than 70?
Question 3 of 20 0.0/ 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.
Question 4 of 20 5.0/ 5.0 Points
Decide which of the described variables likely have a normal or near-normal distribution. 1. The number of credits remaining until graduation for the students in a small liberal arts college 2. The heights of male students in an advanced placement mathematics class 3. The number of sixes showing when two dice are rolled A. a B. b C. c D. None
Question 5 of 20 5.0/ 5.0 Points The amount of Jen’s monthly electric bill is normally distributed with a mean of \$160 and a standard deviation of \$14. Fill in the blanks. 95% of her electric bills are between __________ and __________. Apply the 68-95-99.7 rule to this question.
Question 6 of 20 5.0/ 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?
Question 7 of 20 5.0/ 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.
Question 8 of 20 5.0/ 5.0 Points Decide which of the described variables likely have a normal or near-normal 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 9 of 20 5.0/ 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, what percentage of light bulbs have a life less than 2500 hours?
Question 10 of 20 5.0/ 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.