9. [-/4.42 Points] DETAILS BBUNDERSTAT12 7.4.014.5. MY NOTES ASK YOUR TEACHER Independent random samples of professional football and basketball players gave the following information. Assume that the weight distributions are mound-shaped and symmetric. Weights (in lb) of pro football players: x1; nj = 21 247 263 254 251 244 276 240 265 257 252 282 256 250 264 270 275 245 275 253 265 272 Weights (in lb) of pro basketball players: x2; n2 = 19 204 200 220 210 193 215 223 216 228 207 225 208 195 191 207 196 181 193 201 LA USE SALT (a) Use a calculator with mean and standard deviation keys to calculate x1, $1, x2, and $2. (Round your answers to four decimal places.) X1 = S1 = X2 = $2 - (b) Let #j be the population mean for x1 and let #2 be the population mean for x2. Find a 99% confidence interval for #1 - #2 (Round your answers to one decimal place.) lower limit upper limit (c) Examine the confidence Interval and explain what it means in the context of this problem. Does the interval consist of numbers that are all positive? all negative? of different signs? At the 99% level of confidence, do professional football players tend to have a higher population mean weight than professional basketball players? Because the interval contains only negative numbers, we can say that professional football players have a lower mean weight than professional basketball players. Because the interval contains both positive and negative numbers, we cannot say that professional football players have a higher mean weight than professional basketball players. Because the interval contains only positive numbers, we can say that professional football players have a higher mean weight than professional basketball players. (d) Which distribution did you use? Why? The Student's t-distribution was used because s, and 62 are known. The Student's t-distribution was used because s, and 2 are unknown. The standard normal distribution was used because s, and oz are known. The standard normal distribution was used because , and #2 are unknown. MY NOTES ASK YOUR TEACHER 10. [-/4.42 Points] DETAILS BBUNDERSTAT12 7.4,016.MIS