Statistics

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A. The following scores were observed in a periodical examination administered to a group of 20 students:

75, 82, 85, 87, 88, 83, 86, 77, 76, 76, 77, 89, 90, 91, 92, 88, 83, 80, 77, 74

1. Compute the mean and standard deviation of the examination scores.

Mean is = 82.8

Standard deviation =

2. What are the Z-score and the standard T-score of an examination score of 88? 89?75?

B. Obtain the z-scores of the following raw scores if the scores are normally distributed with mean =30 and standard deviation = 5.

1.) 25

2.) 27

3.) 20

4.) 27.5

5.) 24.8

C. Find the required areas under the normal curve if the scores are assumed to be normally distributed with mean = 50 and standard deviation = 10.

1. To the left of x = 45

2. To the right of x = 53

3. Between 53 and 63

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