Question

The mean of a set of credit scores is 690 and 14. Which credit score is within a z-score of 3.3?

634
640
720
750

Answer 1

C. 720.

Explanation:

We have been given that the mean of a set of credit scores is 690 and standard deviation is 14.

To find the credit score that is within a z-score of 3.3 we will use z-score formula.

`z=(x-\mu)/(\sigma)`, where,

`z=\text{z-score}`,

`x=\text{Raw score}`,

`\mu=\text{Mean}`,

`\sigma=\text{Standard deviation}`.

Upon substituting our given values in above formula we will get,

`3.3=(x-690)/(14)`

Let us multiply both sides of our equation by 14.

`3.3*14=(x-690)/(14)*14`

`46.2=x-690`

Let us add 690 to both sides of our equation.

`46.2+690=x-690+690`

`736.2=x`

Upon looking at our given values we can see that credit score 720 is within a z-score of 3.3, while 750 is above our given z-score, therefore, option C is the correct choice.