Question

As an introduction to probability, a student is asked to roll a fair, six-sided number cube seven times. The results of those seven rolls are shown below.

1, 4, 4, 4, 4, 6, 5

What is the standard deviation of the data?

1.41
1.53
2.33
5

Answer 1

B: 1.53

Explanation:

The mean, or average, is 4, and n, the amount of numbers, is 7. To find the standard deviation, first, all of the numbers are subtracted by the mean. This makes (-3, 0, 0, 0, 0, 1, 2). Square all of them to get (9, 0, 0, 0, 0, 1, 4). Next add the squared numbers together (9 + 0 + 0 + 0 + 0 + 1 + 4 = 14). Next, the variance needs to be found. That is found by this formula: (Sum of previous number set ÷ (n - 1)). So in this case, (14 ÷ (n - 1)). Since n is 7, it is (14 ÷ (7 - 1)), or (14 ÷ 6). The answer to that is 2.3 repeating. After the variance is found, it is square rooted to get the standard deviation. √2.3 is about 1.53. Hope this helps! Have a great day! :)