Question

19) 3) A test is administered annually. The test has a mean score of 150 and...

19)

3) A test is administered annually. The test has a mean score of 150 and a standard deviation of 20. If Ravi’s z-score is 1.50, what was his score on the test?

A) 180
B) 130
C) 30
D) 150
E) None of the above

87)A random sample of 40 college professors is selected from all professors at a university. The following list contains their ages. 65, 45​, 44​, 38, 55​, 55​, 49​, 42​, 43​, 22​, 52​, 58​, 52​, 38​, 56​, 34​, 53​, 36​, 50​, 36 34​, 68​, 43​, 56​, 37​, 35​, 28​, 30​, 26​, 26​, 53​, 30​, 37​, 55, 28​, 39​, 26​, 31​, 37​, 50

The percentile rank of the age 55 is?

Homework Answers

Answer #1

19

This is a normal distribution question with
z = 1.5

The z-score at x = 180.0 is,

OPTION A

87)
Take note that there are 40 data values in this data set. It's helpful to sort them in ascending order.

22.0, 26.0, 26.0, 26.0, 28.0, 28.0, 30.0, 30.0, 31.0, 34.0, 34.0, 35.0, 36.0, 36.0, 37.0, 37.0, 37.0, 38.0, 38.0, 39.0, 42.0, 43.0, 43.0, 44.0, 45.0, 49.0, 50.0, 50.0, 52.0, 52.0, 53.0, 53.0, 55.0, 55.0, 55.0, 56.0, 56.0, 58.0, 65.0, 68.0

Percentile Rank = [(M + (0.5 * R)) / Y] x 100

• M = Number of Ranks below x = 32
• R = Number of Ranks equals x = 3
• Y = Total Number of Ranks = 40

Percentile Rank = [(32 + (0.5 * 3)) / 40] x 100
Percentile Rank = (33.5/40) x 100
Percentile Rank = 83.75 or 84th rank

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