Exhibit 16

Multiple Choice

Exhibit 16.2 A researcher wishes to estimate the average annual expenditures per household on gasoline.The estimate must be accurate within plus or minus $50 and the estimated standard deviation for such expenditures is $400.
Refer to Exhibit 16.2.For a 95%-confidence interval (use z = 2) ,the required sample size is

A) 250.
B) 128.
C) 256.
D) 640.
E) Not enough information given.