Salaries of 11 college graduates who took a statistics course in college have a​ mean of $77,261 and a standard​ deviation of $1,052​. Assume that prior studies have shown that the standard deviation of salaries of college graduates who have taken a statistics course in college is $2000. Construct a 90​% confidence interval for estimating the population mean. Enter the upper bound of the confidence interval. (Round your answer to nearest whole dollar.)

Salaries of 11 college graduates who took a statistics course in college have a​ mean of $79,136 and a standard​ deviation of $1,240​. Construct a 95​% confidence interval for estimating the population mean. Enter the upper bound of the confidence interval. (Round your answer to nearest whole dollar.)

John wishes to estimate the population mean salary of college graduates who took a statistics course in college. How many college graduates must he survey? Assume that the population standard deviation is known to be $1,210, and he wants to be 99% confident that the sample mean is within $167 of the true population mean.

Salaries of 11 college graduates who took a statistics course in college have a​ mean of $88,357 and a standard​ deviation of $1,699​. Construct a 98​% confidence interval for estimating the population standard deviation. Enter the upper bound of the confidence interval. (Round your answer to nearest whole dollar.)

John wishes to estimate the population standard deviation of salary of college graduates who took a statistics course in college. How many college graduates must he survey? Assume that he wants to be the sample standard deviation to be within 50% of the population standard deviation and to be 99% confident of that statement.