The mean score on a certain standardized test is 500, with a standard deviation on 75. Jessie scored in the 75th percentile. What was Jessie's score and the z score?

Please help as soon as possibel. thx

The mean score on a certain standardized test is 500, with a standard deviation on 75. Jessie scored in the 75th percentile. What was Jessie's score and the z score?

Please help as soon as possibel. thx

Please help as soon as possibel. thx

- stapel_eliz
**Posts:**1731**Joined:**Mon Dec 08, 2008 4:22 pm-
**Contact:**

FWT wrote:The mean score on a certain standardized test is 500, with a standard deviation on 75. Jessie scored in the 75th percentile. What was Jessie's score and the z score?

They should have given you some sort of

. . . . .

In your case, you have:

. . . . .

A score in the 75th percentile represents a score which is greater than 75% of all of the scores. With respect to the standard-normal curve, it represents the probability that a given score Z will be in the lower 75% of the scores: P(Z < z) = 0.75. Depending on the table (or calculator) you're using, this value will be something close to 0.674. Then:

. . . . .

Solve this for Jessie's score X.

Hope that helps!

thanks i got it