Question 1 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 2 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 3 of 20

5.0 Points

Which of the following statements concerning areas under the standard normal curve is/are true?

a) If a z-score is negative, the area to its right is greater than 0.5.

b) If the area to the right of a z-score is less than 0.5, the z-score is negative.

c) If a z-score is positive, the area to its left is less than 0.5.

A. a, c

B. b, c

C. a, b

D. a

Question 4 of 20

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?

A. 19.46%

B. 12.85%

C. 2.87%

D. 13.46%

Question 5 of 20

5.0 Points

The weights of the fish in a certain lake are normally distributed with a mean of 20 lb and a standard deviation of 6. If 9 fish are randomly selected, what is the likelihood that the mean weight will be between 17.6 and 21.6 lb?

A. 0.9370

B. 0.6800

C. 0.6730

D. 0.0968

Question 6 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%

Question 7 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 8 of 20

5.0 Points

At one college, GPAs are normally distributed with a mean of 2.9 and a standard deviation of 0.6. Find the 70th percentile.

A. 3.53

B. 3.42

C. 3.23

D. 3.13

Question 9 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 10 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

Which of the following statements concerning the standard normal curve is/are true (if any)?

a) The area under the standard normal curve to the left of-3 is zero.

b) The area under the standard normal curve between any two z-scores is greater than zero.

c) The area under the standard normal curve between two z-scores will be negative if both z-scores are negative.

d) The area under the standard normal curve to the left of any z-score is less than 1.

A. a, b

B. b, d

C. a, c

D. a

Question 12 of 20

5.0 Points

The mean score on the exit examination for an urban high school is 63 with a standard deviation of 8. What is the mean of the distribution of sample means with a sample size of 9?

A. 62

B. 63

C. 63.5

D. 64

Question 13 of 20

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 14 of 20

5.0 Points

A study of the amount of time it takes a mechanic to rebuild the

transmission for a 1992 Chevrolet Cavalier shows that the mean is 8.4

hours and the standard deviation is 1.77 hours. Assume that a random

sample of 40 mechanics is selected and the mean rebuild time of the

sample is computed. Assuming the mean times are normally distributed,

what percentage of sample means are greater than 7.7 hours?

A. 0.62%

B. 34.46%

C. 65.54%

D. 99.38%

Question 15 of 20

5.0 Points

The annual precipitation amounts in a certain mountain range are normally distributed with a mean of 88 inches, and a standard deviation of 10 inches. What is the likelihood that the mean annual precipitation during 25 randomly picked years will be less than 90.8 inches?

A. 0.4192

B. 0.5808

C. 0.0808

D. 0.9192

Question 16 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

D. neither

Question 17 of 20

5.0 Points

The systolic blood pressures of the patients at a hospital are normally distributed with a mean of 136 mm Hg and a standard deviation of 12 mm Hg. Find the two blood pressures having these properties: the mean is midway between them and 76.98% of all blood pressures are between them.

A. 121.6, 152.4

B. 121.6, 150.4

C. 123.6, 150.4

D. 122.6, 148.4

Question 18 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, what percentage of light bulbs have a life less than 2500 hours?

A. About 25%

B. About 50%

C. About 75%

D. About 68%

Question 19 of 20

5.0 Points

The amount of Jens monthly phone bill is normally distributed with a mean of $50 and a standard deviation of $10. Find the 25th percentile.

A. About $46.30

B. About $43.30

C. About $43.40

D. about $43.20

Question 20 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%