A manager of credit department at Selma stories wants to estimate the mean balance due on customers’ accounts. A Random sample of 25 accounts is drawn and it is found that their mean balance is 231.34$. While the mean balance changes from month to another, experience suggests that the stander deviation in the balances due is approximately constant is 84.37$. Find 1- Construct 90% confidence Interval (C.L) for the mean balance of the customers’ accounts at Selma stories. And comment on the results. 2- Construct 95% confidence Interval (C.L) for the mean balance of the customers’ accounts at Selma stories. And comment on the results. 3- Without any computation, state what do you expect to happen if the confidence level changes from 90% to 99% 4- What is the smallest sample size if the manager wants that the confidence length doesn’t exceed 60$ with confidence 95%
A manager of credit department at Selma stories wants to estimate the
Find
1- Construct 90% confidence Interval (C.L) for the mean balance of the customers’ accounts at Selma stories. And comment on the results.
2- Construct 95% confidence Interval (C.L) for the mean balance of the customers’ accounts at Selma stories. And comment on the results.
3- Without any computation, state what do you expect to happen if the confidence level changes from 90% to 99%
4- What is the smallest sample size if the manager wants that the confidence length doesn’t exceed 60$ with confidence 95%
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