Which answer is the approximate standard deviation of the data set?

3.4

Step-by-step explanation:

Standard deviation of a population is defined as:

σ² = ∑(xᵢ − μ)² / n

The standard deviation of a sample is defined as:

s² = ∑(xᵢ − x)² / (n - 1)

It's not clear which one we have, so let's calculate both.

First, we must find the mean.

μ = (5+12+15+10+12+6+8+8) / 8

μ = 9.5

Now we find the squares of the differences:

(5-9.5)² + (12-9.5)² + (15-9.5)² + (10-9.5)² + (12-9.5)² + (6-9.5)² + (8-9.5)² + (8-9.5)²

= 80

Divide by n:

σ² = 80 / 8

σ² = 10

And take the square root:

σ = √10

σ ≈ 3.2

That's not one of the answers, so let's try the standard deviation of a sample instead of a population.

Instead of dividing by n, we'll divide by n-1:

s² = 80 / 7

And take the square root:

s = √(80/7)

s ≈ 3.4

So that must be it.

7 is the median   7.875 is the mean

step-by-step explanation:

3,4,5,6,8,11,13,13