Consider the mean combined SAT score for high school seniors is 1500, "Consider the mean combined SAT score for high school seniors is 1500, and the standard deviation is 250. Calculate the percentage of students who scored at the following levels"...
Can anyone figure out what this question is asking for? I can find a Z-score then a corresponding probability but I don't think that's what they want... 
 A: It's difficult to guess from this fragment. If this is at the beginning of
using normal distributions in a basic probability or statistics course, my
guess is they want you to standardize and use printed normal tables (or
possibly software).
Assuming that the population is normal with mean $\mu = 1500$ and SD $\sigma = 250,$ you could find proportions of students in the population with scores
in various ranges. By the Empirical Rule (essentially exact for normal
populations), you would expect 95% of the population to have scores in
the interval $\mu \pm 2\sigma$ or $1500 \pm 500.$
The exact result from R software is 95.45%: 
 diff(pnorm(c(1000,2000), 1500, 250))
 ## 0.9544997

or
 diff(pnorm(c(-2,2)))
 ## 0.9544997

To use printed tables of the standard normal distribution, you would begin
as follows:
$$P(1000 < X < 2000) = 
P\left(\frac{1000 - 1500}{250} < \frac{X - \mu}{\sigma} < \frac{2000 - 1500}{250} \right) \\= P(-2 < Z < 2) = \dots,$$
where $Z$ is standard normal.
Similarly, you could find the proportion of the population scoring above 1800, or below 1450, or between 1450 and 1500, and so on.
Note: Essentially this is the same guess as in the Comment by @MorganRodgers posted while I was typing my Answer.
