The mean is 100. Standard Deviation is 16 on a normal curve.

The question is:

If the distribution of mental ability scores is normal, the middle 68 percent of the scores should lie between what two scores?

answer: 84 to 116. How do you find this?

The next question is:

The middle 96 percent of the mental ability scores should be between what two values?

answer: 68 to 132

Its killing me.