Binomial Probability Distributions

I am having alot of difficulty in my bio-statistics class can anyone help with these 2 questions?

Create pmf and histogram before answering these question. ( I am not sure how to do a pmf and histogram for this question )

Problem #1: Telephone Survey: A telephone survey uses a random digit dialing maching to call subjects. The random digit dialing machine is expected to reach a live person 15% of the time. In eight attempts, what is the probability of achieving exactly two successful calls?
( You should produce a PMF & Histogram for Binomial Distribution before you answer the question ).

** Problem #2 is a continuation of problem #1 **
Problem #2: Problem #1 introduced a random digit dialing maching with p=0.15 for each call attempt.
(a) What is the expected value and variance for the number of contacts in eight attempts?
(b) What is the expected value and variance for 50 attempts?

Can anyone PLEASE help me.... Thank you very much...

Problem #1: Telephone Survey: A telephone survey uses a random digit dialing maching to call subjects. The random digit dialing machine is expected to reach a live person 15% of the time. In eight attempts, what is the probability of achieving exactly two successful calls?
( You should produce a PMF & Histogram for Binomial Distribution before you answer the question ).

Click to expand...

Yes, use the Binomial probability. \(\displaystyle \binom{n}{k}p^{k}(1-p)^{n-k}\)

\(\displaystyle \binom{8}{2}(.15)^{2}(.85)^{6}\)