Question

i need help with the question 13.2

13.2 Answer the following for the data of Exercise 12.11: a. What is the 10-percentile and 90-percentile from the sample? b. What is the mean number of disk VO's per program? c, what is the 90% confidence interval for the mean? d. What fraction of programs make less than or equal to 25 LO's and what is the 90% confidence interval for the fraction? e, what is the one-sided 90% confidence interval for the mean?

Answer 1

Following is the ordered data set and calculations for mean and SD:

Sample size: n=33

(a)

The 10th percentile will be

Since 3rd data value is 13 and 4th data value is 14 so required percentile is

--------------------

The 90th percentile will be

Since 30th data value is 38 and 31st data value is 39 so required percentile is

b)

Mean:

c)

Standard deviation:

Confidence interval:

d)

Out of 33 data values, 16 are less than equal to 25 so required fraction is

Confidence interval:

e)

The critical value for one sided confidence interval is $z_{0.90}=1.28$

The one sided confidence interval for mean is

·24336 9.4946 = 29.08 +tcriticalyM = 26.96 + 1.28 Vn

The one sided confidence interval is (-infinity, 29.08).