Question

Suppose you want to estimate the average mpg for cars being driven from campus to the Brass Rail. You sample a few of cars. The average mpg in your sample is 22, and the standard deviation is 10. If you want the error of the confidence interval to be no greater than 0.3 and to be 90% likely to contain the true population mean, how many cars should you randomly sample?

Group of answer choices

A)about 3,007 cars

B)about 9,112 cars

C)about 311 cars

D)about 942

E)This question cannot be answered using the information given

Answer 1

We have given here,                  
                  
Standard deviation =10  
Margin of error =E=0.3  
Level of significance =1-0.90=0.1  
Z critical value is (by using Z table)=   1.645  
Sample size formula is                   


=3006.69

A)about 3,007 cars