The scores on a college entrance exam is 100 with a standard deviation of 7.5. How do you find the probability that a randomly selected score is between 85 and 100?

1 Answer
Jun 22, 2017

Proability that a randomly selected score is between 85 and 100 is 47.72%

Explanation:

Asumming that the distribution is normal, let us find the z score of 85 and 100.

As mu=100 and sigma=7.5

z-score is given by (x-mu)/sigma

Hence for 85, z-scorre is (85-100)/7.5=-15/7.5=-2

and for 100, z-scorre is (100-100)/7.5=0

Hence area between -2 and 0 from tables is 0.4772

and probability is 47.72%

[See more here.](https://socratic.org/questions/the-area-under-the-normal-curve-between-z-1-0-and-z-2-0#443143)