Although studies continue to show smoking leads to significant health problems, 20% of adults in the United

Question:

Although studies continue to show smoking leads to significant health problems, 20% of adults in the United States smoke. Consider a group of 250 adults.
a. What is the expected number of adults who smoke?
b. What is the probability that fewer than 40 smoke?
c. What is the probability that from 55 to 60 smoke?
d. What is the probability that 70 or more smoke?