Starting from the same place, sara walks due west and ammad walks due east. on the number line, 0 represents their starting point, negative values represent the distance traveled west and positive values represent the distance traveled east. a number line with a point for ammad at coordinate 480 and a point for sara at coordinate -240. how many feet apart are sara and ammad on the number line? enter your answer in the box.

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.