Question

Alice was told that her reading test score was 1 standard deviation below the mean. If test scores were approximately normal with μ=86 and σ=4, what was Alice's score? Do not include units in your answer. For example, if you found that the score was 86 points, you would enter 86.

Answer 1

it's 68

Explanation:

Answer 2

82

Explanation:

Given that the population mean μ=86 and standard deviation σ=4 then one standard deviation below the mean means 4 less than 86 which is 82.

or

One standard deviation below the mean means z=-1 where z* is the z*score value in the standard normal distribution

Apply the formula

z=(x-μ)/σ

where x=Alice's score

μ=estimate mean

σ=standard deviation

z=(x-μ)/σ

-1=(x-86)/4----------------cross multiply

-1*4=x-86

-4=x-86

-4+86=x

82=x