Question

1) It is known that 10% of the calculators shipped from a particular factory are defective. What is the probability that exactly three of five chosen calculators are defective?

A) 0.00729

B) 0.0081

C) 0.081

D) 0.03

2)For a particular clothing store, a marketing firm finds that 16% of $10-off coupons delivered by mail are redeemed. Suppose six customers are randomly selected and are mailed $10-off coupons. What is the expected number of coupons that will be redeemed?

A) 0.81

B) 0.96

C) 3.42

D) 5.04

3)

The GPA of accounting students in a university is known to be normally distributed. A random sample of 20 accounting students results in a mean of 2.92 and a standard deviation of 0.16. Construct the 95% confidence interval for the mean GPA of all accounting students at this university.

A) 2.92 ± 1.729(0.16/ )

B) 2.92 ± 1.96(0.16/ )

C) 2.92 ± 2.086(0.16/ )

D) 2.92 ± 2.093(0.16/ )

4)

The probability that a normal random variable is less than its mean is ________.

A) 0.0

B) 0.5

C) 1.0

D) Cannot be determined

5)

A company that produces computers recently tested the battery in its latest laptop in six separate trials. The battery lasted 8.23,7.89,8.14,8.25,8.30, and 7.95 hours before burning out in each of the tests. Assuming the battery duration is normally distributed, construct a 95% confidence interval for the mean battery life in the new model.

A) [7.9490, 8.3044]

B) [7.9575, 8.2959]

C) [7.9873, 8.2661]

D) [7.9912, 8.2622]

Answer 1