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 sample size b. increase the sample mean c. increase the confidence coefficient d. decrease the sample size e. increase the population size

a. increase the sample size

Step-by-step explanation:

The width of a confidence interval is twice the margin of error, which is given by:

In which is the standrd deviation of the population, n is the size of the sample, and z is the confidence coefficient(the higher the confidence level, the higher z is).

The only of those variables which is direct proportional to M is the sample size. This means that if we want to decrease the width of M, we need to increase the sample size.

So the correct answer is:

a. increase the sample size

b: |12 – x| ≤ 0.25

step-by-step explanation:      

let x be the possible lengths in inches, of the ribbons jaime cut.

we have been given that jaime is cutting strips of ribbon for a project. he tries to cut each piece to be 12 inches long, but sometimes he cuts it too long or too short by as much as 0.25 inch.  

we can represent this information in an inequality as:

by the definition of absolute value function we will get,

upon combining our inequalities we will get,

therefore, the inequality   describes all the possible lengths (x), in inches, of the ribbons jaime cut.

step-by-step explanation:

the answer is $42.96

step-by-step explanation: