Question

Mr. Crandall has assigned a term paper due at the end of the semester. He would like to know the average length of the papers. The data below are the he numbers of types pages from a random sample of 10 term papers. Use these data to compute a 95% confidence interval for the population mean length of all term papers for his class. Interpret the interval in the context of this problem. 14, 20, 25, 10, 16, 8, 15, 12, 18, 9. State what assumptions were met to use the method you selected. Check for the normal distribution of the population.

Answer 1

Find the mean first = sum of scores/number of scores

Subtract each of the scores from the mean and square each difference. Find the sum of these squares. Divide that by the number of scores to get variance.

Standard deviation = square root of variance

95% = mean ± 1.96 SD

I'll let you do the calculations.

Answer 2

(16.66,12.74)