Question

PLEASE ANSWER ALL QUESTIONS

1. The number of new customers per day has typically averaged 8.1 per day at a fitness center for many years. The standard deviation has been 1.8. After the executive director raises concerns that the number of new clients is declining, Derek takes a sample of the most recent 36 days and finds that the mean is 7.8 new customers.

What is the standard error of the mean?

Select one:

a. 0.1

b. 0.3

c. 1.3

d. 1.6

e. 1.7

2. What z-value is used to calculate an 85% level of confidence?The standard deviation is 12. The sample size is 56 and the sample mean is 33.

Select one:

a. 1.44

b. 1.03

c. 1.96

d. 0.30

e. 1.65

Answer 1

Solution :

Given that ,

standard deviation = = 1.8

n = 36

stnadrad error

= / n = 1.8/ 36 = 0.3

2.

At 85% confidence level the z is ,

= 1 - 85% = 1 - 0.85 = 0.15

/ 2 = 0.15 / 2 = 0.075

Z/2 = Z0.075 =1.44 ( Using z table )