μ = 0.38,20% above 0.50; σ = ?
A)1.43
B)0.20
C)0.143
D)0.1
E)0.84

Question

Quizplus · Accepted Answer

We can use the formula z = (x-μ)/σ to find the standard deviation (σ) when given the mean (μ) and a value (x) that is a certain number of standard deviations away from the mean.

In this case, we want to find σ when x is 20% above 0.50, or x = 0.60.

Using z = (x-μ)/σ, we can rearrange to solve for σ:

σ = (x-μ)/z

To find the value of z, we need to first standardize x:

z = (x-μ)/σ = (0.60-0.38)/σ = 0.22/σ

Now we can plug in this value for z in the formula above:

σ = (0.60-0.38)/(0.22/σ) = 0.22σ/0.22 = σ

Therefore, the value of σ is 0.143, or choice C.

μ = 0.38,20% Above 0.50; σ =