1. ## Normal distribution

I have a question about how to show the work for this and how to solve it also
Here is the problem:
The verbal part of the GRE has a mean of 500 and a standard deviation of 100. Use the normal distribution to answer the questions:
a. if we wanted to select only students at or above the 90th percentile, what verbal gre score would we use as a cutoff? I got the answer 628.01 but unsure about how to show my work
b.what verbal gre score corresponds to a percentile rank of 15%. 55%?
c what is the precentile rank of a verbal gre score of 628? 350?
d if we randomly selcted 1,500 students who had taken the verbal gre how many would we expect to score lower than 250? higher than 750?

2. ## Re: Normal distribution

For he first one...

$\displaystyle P\left( Z> \frac{x-500}{100}\right) = 0.9$

3. ## Re: Normal distribution

how would that be worked out?

4. ## Re: Normal distribution

In the normal distribution table, find the value of $\displaystyle Z_0$ such that

$\displaystyle P\left( Z> Z_0) = 0.9$

Make the result equal to $\displaystyle \frac{x-500}{100}$ and solve for $x$