Intro Stats Unit 2 Practice Test MC

Question #1

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Answer explanation

Percentile is the percent of values less than a given value. If Pete's score was at the 73rd percentile, then 73% of the class scored worse than Pete. Which also means that Pete did better than 73% of his class.

Question #2

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Answer explanation

Area = length x height

In this example, the length is 1.2 - 0.5 = 0.7 and the height is 1/2.

Multiply 0.7 x 1/2 to get 7/20 = 35%

Question #3

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Answer explanation

First, since we are finding the 28th percentile, we know the z-score has to be negative, since the 50th percentile is approximately at zero. You have two ways to solve..

1) Table A: Find the z-score with a left tail area value closest to 0.2800

2) Stapplet: Normal distribution with a mean of 0 and an SD of 1. Enter area = 0.28

Question #4

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Answer explanation

The mean is 2. A normal distribution shows 3 standard deviations from the mean. The curve appears to end at 11. The distance from the 11 to 2 is 9. Divide that by 3 to get 3.

Question #5

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Answer explanation

Plug the given values into the z-score equation and solve for x.

Question #6

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Answer explanation

USE EMPIRICAL RULE: 2 grams is two SD above the mean. Approximately 5% of values are above/below 2SD from the mean. Take 5% and divide it in half to get the percent above = 2.5%

Question #7

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Answer explanation

D is the only answer that we know is 100% true.

Question #8

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Answer explanation

Use table A to find z-score with a left tail area of .8600. Then plug all values in to the z-score formula and solve for SD.

Question #9

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Answer explanation

Calculate the z-score for each and the car with the higher z-score is the more expensive car relative to other cars in their respective year.

Question #10

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Answer explanation

A standardized distribiution (Mean = 0 and SD = 1) will always have the same shape as its original distribution.