Question

1. A large company is considering provision of a dental insurance plan for its executives. In a random sample of n = 25 executives the mean family dental expenses in the previous year was $2800.60, and the standard deviation S = $1287.40. To calculate a 90% confidence interval for the mean annual family dental expenses of a company executive they should use

Select one:

a. a binomial distribution with n = 25.

b. a normal distribution.

c. a t-distribution with 25 degrees of freedom.

d. a t-distribution with 24 degrees of freedom.

2. The lengths of calls made to a call centre of a telecommunications company is known to be normally distributed with a mean of 15 minutes and a standard deviation of 5 minutes.   The probability that a randomly chosen call lasts for 25 minutes or more is closest to:

Select one:

a. 0.150

b. 0.300

c. 0.025

d. 0.050

3. Referring back to question 2, approximately 15% of calls last less than how many minutes?

Select one:

a. 15 minutes

b. 10 minutes

c. 5 minutes

d. 1 minute

4. The probability that a mortgage foreclosure is due to disability is known to be 0.48. If a large lending institution audits 40 mortgage foreclosures then, assuming a Binomial distribution, the expected number of mortgage foreclosures due to disability is closest to：

Select one:

a. 4

b. 10

c. 19

d. 21

5.The mortgage manager estimates that it takes her 45mins to process each approved mortgage. Her expected weekly time spent processing approved mortgages is closest to:

Select one:

a. 45 minutes

b. 90 minutes

c. 126 minutes

d. 135 minutes

6. A mortgage manager at a local bank records the number of home mortgages she approves per week for an extended period of time and comes up with the following probability distribution:

Number of mortgages approved per week	0	1	2	3	4	5	6
Probability	0.10	0.10	0.20	0.30	0.15	0.10	0.05

Q14. The probability that she approves four or more mortgages in a given week is closest to:

Select one:

a. 0.15

b. 0.30

c. 0.46

d. 0.70

Answer 1

1.

d. a t-distribution with 24 degrees of freedom.

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2.

Ans :

c. 0.025

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3.

Ans:

b. 10 minutes

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