A random sample of 100 lightning flashes resulted in a sample average radar echo duration of .81 sec. Assume that the observations are random sample from the normal distribution with standard deviation of 34 sec. (part a) Test if the true average echo duration is longer than .75 sec. Report p-value. (H, u = 75.HA : 11 >.75) 22. (part b) Does above data show statistical evidence that the true mean echo duration is longer than 75 sec? Use 5% significance level to answer.