Question

14. A survey of 30 emergency room patients found that the average waiting time for treatment was 174.3 minutes. Assuming that the population standard deviation is 46.5 minutes, find the 99 percent confidence interval of the population mean.

NOTE: be sure to take the square root of a given Variance in the word problems to obtain the standard deviation and use that for your figuring

a. 142.4, 188.2

b. 152.4, 196.2

c. 170.2, 178.3

d. 180.1, 194.9

Answer 1

n = sample size = 30

= sample mean = 174.3

= population SD = 46.5

# 99 percent confidence interval of the population mean . when is known

=1-c%=1-0.99=0.01

Z/2=Z0.01/2=2.58

Value of z is obtain from standard normal table

(174.3-21.868,174.3-21.868)

(152.4,196.2)

#Option b is correct