c what percentage of compounds formed from the extract of this plant f

Question

The extract of a plant native to Taiwan has been tested as a possible treatment for Leukemia. One of the chemical compounds produced from the plantwas analyzed for a particular collagen. The collagen amount was found to be normally distributed with a mean of 71 and standard deviation of 6.5grams per mililiter. (a) What is the probability that the amount of collagen is greater than 66 grams per mililiter? (b) What is the probability that the amount of collagen is less than 79 grams per mililiter? (c) What percentage of compounds formed from the extract of this plant fall within 1 standard deviations of the mean?