In a manufacturing process a random sample of 9 bolts manufactured has a mean length of 3 inches with a standard deviation of .3 inches. What is the 95% confidence interval for the true mean length of the bolt?
A. 2.804 to 3.196
B. 2.308 to 3.692
C. 2.769 to 3.231
D. 2.412 to 3.588
E. 2.814 to 3.186

The correct option is (C) (2.769, 3.231).

Step-by-step explanation:

The confidence interval for mean when the standard deviation is not known is:

Given:

Compute the critical value as follows:

**Use a t-table.

The 95% confidence interval for true mean length of the bolt is:

Thus, the 95% confidence interval for true mean length of the bolt is (2.769, 3.231).

The correct option is (C).

amount of oatypop that contains the prize = 40%

amount   of oatypop which doesn't contain the prize = (100-40)=60%

probability that hannah will win a prize

    = s +f s +f f s+ff   f s+ff f f s+ infinity.where f= failure,s= success

=   or 60%

probability that hannah only has to buy 3 or less boxes before getting a prize= (s) and ( f s) and (ff s) and (f f f s)

        = = 87.04 %  

step-by-step explanation: