(9 marks) I claim to curve STAT 201 grades according to the N(65,10) distribution. A random...

I claim to curve STAT 201 grades according to the N(65,10) distribution. A random sample of 20 grades from a previous class is available in the file grades.csv. You may assume for the purposes of this question that these grades are observations from a normal distribution with standard deviation = 10.

"Grade" 62 74 67 46 60 63 42 69 51 58 71 75 56 55 55 65 45 61 59 60 "= (grade.csv file)

a. Compute a 95% confidence interval for , the actual mean mark in the previous class

b. Provide a formal interpretation of your confidence interval in a) in words. (What does “95% confidence” mean?)

c. Do you think that the actual mean mark in the previous class was 65? Explain.

d. How large would the random sample of grades need to be for a 90% confidence interval to have a total width of 6?

Expert Solution

orchestra answered 1 year ago

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