Posted by Artmisha on .
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 
Damon,
http://easycalculation.com/statistics/standarddeviation.php

Statistic 
Damon,
5.
115  100 = 15
z score means how many standard deviations away from mean
so
15/10 = 1.5
A+ :) 
Statistic 
PsyDAG,
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 = (scoremean)/SD