Question

13) Weights of population of men has  the mean of 170 pounds and the standard deviation of 27 pounds. Suppose 81 men from this population are randomly selected for a certain study

The distribution of the sample mean weight is

a)exactly normal, mean 170 lb, standard deviation 27lb

b) approximately Normal, mean 170 lb, standard deviation 0.3 lb

c)approximately Normal, mean 170 lb, standard deviation 3  lb

d)approximately Normal, mean equal to the observed value of the sample mean, standard deviation 27 lb.

Answer 1

Q.13) Given that, mean (μ) = 170 pounds (lb)

and standard deviation = 27 pounds (lb)

sample size (n) = 81

Since, the sample size is large (n > 30), the sampling distribution of the sample mean is approximately normal.

The mean and standard deviation of the sampling distribution of the sample mean are,

Answer : c) approximately Normal, mean 170 lb, standard deviation 3 lb