Question

Chapter IU! Hypothesis Testing Exercises (1): A random sample of 6 steel beams has a mean com- pressive strength of 58,392 psi (pounds per square inch) with a standard deviation of 648 psi. Use this information and the level of significance a = 0.05 to test whether the true average compressive strength of the steel from which this sample came is 58,000 psi. Assume normality. Roelve the show verrien ifn-en 5. tereo Head Exercises (2): Studying the flow of traffic at two busy intersections between 4 P.M. and 6 P.M. (to determine the possible need for turn signals), it was found that on 40 week- days there were on the average 247.3 cars approach- ing the first intersection from the south that made left turns while on 30 weekdays there were on the average 254.1 cars approaching the second intersection from the south that made left turns. The corresponding sam- ple standard deviations are si = 15.2 and so = 18.7. (a) Test the null hypothesis 1 - 2 = 0 against the alternative hypothesis Hi-M2 + 0 at the level of significance a = 0.01. (Assume the equality of two population variances)

Answer 1

Solution Exercites Given, n 6, 58,332 PsI, S 648 psi ,0.05 Here, we daim that, Ho: M58,000 Ps t58, o00 Psi Hi Hence, Test statistic is, 2 = 58,392 S8,000 6५8 | Vn 392 648 N6 392 264. 5545 Zcal. 4817 level ob significance (K) = 0-05 d2-t.96 Thus Z4121z1 e. we tal to gject Ho can conclude that, we dorst have conclusion-Hence, we Subbicient evid ence to reject the claio that Mean is differ trom s8,0Dops at 0.05