A manufacturer reported a sample mean = 22.0 g and a sample standard deviation = 2.5 g based on a sample of 20 of their products. They hope to design future quality control tests to satisfy several criteria: • The calculated error for a sample set (the error is the difference between the true mean and mean of the sample set) does not exceed 2.0 g. • To save money on those tests, they want to collect as few samples as possible. • They want more than 90% of the confidence intervals they calculate to include the true mean. What value of n would you recommend for future tests?

Step-by-step explanation:

Given that a manufacturer reported a sample mean = 22.0 g and a sample standard deviation = 2.5 g based on a sample of 20 of their products.

The margin of error should not exceed 2.0 gm.

For 90% confidence interval to get margin of error 2 gm

we can say that margin of error = 1.645*std error

Std error = std deviation/square root of n

Hence if margin of error should not exceed 2 gm

we have

n should be atleast 5.

But for using normal critical value n should be atleast 30.

So better to have sample size atleast 30.

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.