Question

e. None of these circumstances would prevent us trom using procedures t An SRS of 100 postal employees found that the average time these employees had worked for the postal service was 7years with standard deviation s 2 years. Assume the distribution of the time the population of employees have worked for the postal service is approximately Normal. Which of the following gives the correct 95% confidence interval for the mean time μ the population of postal service employees have worked for the postal service? a. 7#2 b. 7 1984 c. 7 0.525 d. 7±0.4 12. 7±0.2

Answer 1

Solution:- option d. 7 +/- 0.4

Explanation: Given that n = 100, x = 7, s = 2

df = 100-1 = 99, t = 1.984

95% confidence interval for the mean = X +/- t*s/sqrt(n))

= 7 +/- 1.984*2/sqrt(100)

= 7 +/-  0.3968

= 7 +/- 0.4 (rounded)