Question

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; n1 = 21 246 261 255 251 244 276 240 265 257 252 282 256 250 264 270 275 245 275 253 265 272 Weights (in lb) of pro basketball players: x2; n2 = 19 202 200 220 210 193 215 221 216 228 207 225 208 195 191 207 196 183 193 201 (a) Use a calculator with mean and standard deviation keys to calculate x1, s1, x2, and s2. (Round your answers to one decimal place.) x1 = 259.7 Correct: Your answer is correct. s1 = 12.1 Correct: Your answer is correct. x2 = 205.8 Correct: Your answer is correct. s2 = 12.6 Correct: Your answer is correct. (b) Let μ1 be the population mean for x1 and let μ2 be the population mean for x2. Find a 99% confidence interval for μ1 − μ2. (Round your answers to one decimal place.) lower limit 38.9 Incorrect: upper limit 68.8 Incorrect: Your answer is incorrect. please help me find lower and upper limit

Answer 1

b)

degree of freedom v ='min(n1,n2)-1=

18

std error =√(S21/n1+S22/n2)=

3.9130

Point estimate of differnce =x1-x2     =			53.87
for 99 % CI & 18 df value of t=			2.878
margin of error E=t*std error                   =			11.262
lower bound=mean difference-E     =			42.6
Upper bound=mean differnce +E      =			65.1