The scores of one class on the Unit 2 mathematics test are shown in the accompanying diagram. Find the population standard deviation of these scores, to the nearest tenth.

Question

The scores of one class on the Unit 2 mathematics test are shown in the accompanying diagram. Find the population standard deviation of these scores, to the nearest tenth.

 

Unit 2 Mathematics Test
Test Score	Frequency
96	1
92	2
84	5
80	3
76	6
72	3
68	2

Answer 1

The standard deviation measures how far the test scores are from the average. To find it, you will use this formula:

Σ(data point - average)÷(number of data points)

Here's how that looks for this problem:

First, find the average: (1×96 + 2×92 + 5×84 + 3×80 + 6×76 + 3×72 + 2×68) ÷ (1+2+5+3+6+3+2) = 79.455

Second, find Σ(data point - average): 1×(96-79.455) + 2×(92-79.455) + 5×(84-79.455) + ...

Once you have all of these added up, divide by the number of test scores. That's your standard deviation!

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