5(a). Jeffrey an 8yearold esTainshed a mean Time of 16.43 seconds for swimming The 25yard freesTyle wiTh a sTandard deviaTion of 0.8 seconds. His Dad, Frank, ThoughT ThaT Jeffrey could swim The 25-yard freesTyle fasTer using The goggles, so he boughT Jeffrey a new pair of expensive goggles and Times him for 15 25yard freesTyle swims. For These 15 swims, J effrey's mean Time was 16 seconds. Frank ThoughT ThaT The goggles helped Jeffrey To swim fasTer Than The 16.43 seconds. ConducT a hypoThesis TesT aT a = 0.05. Use The criTicaI value approach. Soln. (b). Jane has jusT begun her new job as a salesperSon for a very compeTiTive Company. In a sample of 16 sales calls iT was found ouT ThaT she closed The conTracT for an average value of $108 wiTh a sTandard deviaTion of $12. TesT The hypoThesis ThaT The populaTion mean is aT leasT $100 againsT The alTernaTive ThaT iT is less Than $100 oT ~~ = 0.1. Use The criTicaI value approach. Soln