Heather can complete two problems in ten minutes, and when she started she had three problems done. joel can complete three problems in fifteen minutes, and when he started he had two problems done. if you include the number of problems that were complete when they started, when will they have completed between 30 and 50 problems? which inequality would you use to solve this problem, if x stands for the number of hours that have passed? a.30 ≤ 24x + 5 ≤ 50 b.30 ≤ 5x + 5 ≤ 50 c.30 < 24x + 5 < 50 d.30 < 10x + 5 < 50

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.