Question

pense QUESTION 1 A long distance phone company wishes to estimate the mean duration of long-distance calls originating in California. A random sample of 15 long-distance calls originating in California yields the following call durations, in minutes 2 5 14 11 22 28 32 21 16 15 1 19 12 2 37 Use the data to obtain a point estimate of the mean call duration for all long-distance calls originating in California 15.3 minutes 13.8 minutes 15,8 minutes 13.9 minutes QUESTION 2 In 1995, the men duration of long-distance telephone calls originating in one town was 65 minutes. A long distance telephone company wants to performa hypothesis test to determine whether the mean duration of long-distance phone calls has changed from 1995. Determine the null and alternative hypotheses HO-65 vs H 6.5 HOMS6.5 vs Hu>6.5 H *65 H 6.5 HO: 65 W 65 3 points are QUESTIONS A researcher computed 90% 95% 98% and 99% confidence intervals for a population mean. However, he forgot to record which interval was which, and he cannot find the sample data to allow him to recreate the intervals from scratch. He now needs cely the 90% confidence interval Which one is it? (379, 42.1) (38.4.41.6) (38.1.41.9) (18.7,413)

Answer 1

solution D The point estimate for mean es I sample mean (x)= Ex = 231 = 15.8 2) Here we are testing that mean duration of cally changed from 6-5 min or not. so, the null & alternative hypothery es Hoie l=6.5 ks Hill t6.5 - 3 here we know that as confidence level decreases The caidth of the enterval also decreases. in all given confidence levels 90% is lowest . so this interval will have less width in all the given options, (38.7, 41.3) has وليد عبد - المنح