Simple normal distribution

SIMPLE NORMAL DISTRIBUTION In a recent year, the ACT scores for the math portion of the test were normally distributed, with a mean of 21.1 and a standard deviation of 5.3. 1) Find the probability that a randomly selected high school student who took the math portion of the ACT has a score that is between 19 and 24. 2) Find the probability that a randomly selected high school student who took the math portion of the ACT has a score that is more than 15. 3) If 800 high school students in one county took the math portion of the ACT, how many will have scores less than 12? 4) What test score occurs at the 17% percentile