675 uniforms were bought for the three grades in an elementary school. The ratio of the number of first graders to the number of second graders tot he number of third graders is 2:3:4. Each uniform for the first graders cost $35, while each uniform for second graders cost $5 more. If the total cost for all of the uniformas was $28,500 how much did each uniform for third graders cost

Arandom sample of 15 observations is used to estimate the population mean. the sample mean and the standard deviation are calculated as 172 and 63, respectively. assume that the population is normally distributed. a. with 99 confidence, what is the margin of error for the estimation of the population mean? b. construct the 99% confidence interval for the population mean. c. construct the 95% confidence interval for the population mean. d. construct the 83% confidence interval for the population mean. hint: you need to use excel function =t. inv.2t to find the value of t for the interval calculation.