# Statistic

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For 3 and 4 find the range, variance, and standard deviation. Round to the nearest tenth.

3. Twelve students were given an arithmetic test and the times (in minutes) to complete it were

10, 9, 12, 11, 8, 15, 9, 7, 8, 6, 12, 10

4. The normal daily temperatures (in degrees Fahrenheit) in January for 10 selected cities are as follows.

50, 37, 29, 54, 30, 61, 47, 38, 34, 61

5. If a history test has a mean of 100 and a standard deviation of 10, find the corresponding z score for a test score of 115.

• Statistic -

http://easycalculation.com/statistics/standard-deviation.php

• Statistic -

5.

115 - 100 = 15

z score means how many standard deviations away from mean
so
15/10 = 1.5
A+ :)

• Statistic -

To do the calculations yourself for 3 and 4:

Range = highest score - lowest

Find the mean first = sum of scores/number of scores

Subtract each of the scores from the mean and square each difference. Find the sum of these squares. Divide that by the number of scores to get variance.

Standard deviation = square root of variance

For 5, this is the equation used:

Z = (score-mean)/SD