Does anyone have any idea on how to solve these?

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 plant was analyzed for a particular collagen. The collagen amount was found to be normally distributed with a mean of and standard deviation of grams per milliliter.

(a) What is the probability that the amount of collagen is greater than grams per milliliter?

answer:

(b) What is the probability that the amount of collagen is less than grams per milliliter?

answer:

(c) What percentage of compounds formed from the extract of this plant fall within standard deviations of the mean? answer: %