I'm stuck on this homework question. If someone can just help get me started with the first one I'm sure I can do the rest. I'm just not sure how to begin. Thanks!

Question

1. A production process produces 90% non-defective parts. A sample of 10 parts from the production process is selected.
a. What is the probability that the sample will contain 7 non-defective parts?
b. What is the probability that the sample will contain at least 4 defective parts?
c. What is the probability that the sample will contain less than 5 non-defective parts?
d. What is the probability that the sample will contain no defective parts?

Answer 1

a. 3/4
b. 4/8
c. 1/4
d. 2/7

Answer 2

how did you do them? do you have an equation or anything?