a) Using the given data compute the sample mean and sample standard deviation of these 215 observations.

b)Ignoring the values, you have computed in part (a), now find the expected frequencies assuming a normal distribution model with respective mean and standard deviation of 68.8 and 12.6. Round the expected frequencies you computed to the nearest integer. Perform a Chisquare goodness of fit test to check whether the normal distribution assumed herein with mean 68.8 and standard deviation 12.6 (assume these are given and not computed from the data) is a good fit to the given data at the ? = 2% significance level.

Grade Observed frequency Less than 50 10 50-60 35 60-70 50 70-80 75 80-90 40 90-100 5 Total 215 a) Using the given data compute the sample mean and sample standard deviation of these 215 observations. b)Ignoring the values, you have computed in part (a), now find the expected frequencies assuming a normal distribution model with respective mean and standard deviation of 68.8 and 12.6. Round the expected frequencies you computed to the nearest integer. Perform a Chi- square goodness of fit test to check whether the normal distribution assumed herein with mean 68.8 and standard deviation 12.6 (assume these are given and not computed from the data) is a good fit to the given data at the a = 2% significance level