After constructing a confidence interval estimate for a population mean, you believe that the interval is useless because it is too wide. In order to correct this problem, you need to:.a. increase the population standard deviation b. increase the level of confidence c. increase the sample size d. increase the sample mean e, none of these would help

C. Increase the sample size

Step-by-step explanation: The confidence interval is a interval estimate of two numbers. From the question, the width confidence interval

Can be modified into a more narrow margin by reducing the standard error. The standard error is the value obtained from the division of standard deviation and the square root of sample size. Hence, a decrease in the standard error will give a more narrow confidence interval estimate. The standard error can be reduced by increasing the denominator of the standard error formula which is the sample size.

2nd one in the first row is correct

probability for j is 1/4

while

a is 1/6