Applied Statistics Quiz 9 Name: ID:

Applied Statistics
Quiz 9
Carefully Read The Instructions!
Instructions: This is a take home quiz. It is due at the same time as the last
homework assignment (HW 10) on December 17th.
1. It is assumed that the number of red MandM’s in a large bag of MandM’s is
approximately normally distributed with unknown mean µ and variance 9. A
random sample of 10 large bags of MandM’s was obtained and the number of
red MandM’s in each bag was counted. This data is given in the table below.
Bag Number
1 2 3 4 5
Number of Red MandMs 21 26 18 31 33
6 7 8 9 10
22 25 27 29 30
(a) Compute a 95% confidence interval for µ based on this sample. (Hint:
x̄ = 26.2)
(b) Assume instead that the value of the variance is unknown. Computed
from the sample S = 4.77. Derive a 95% confidence interval for µ.