I am having trouble solving the following question after reading my textbook. Thank you for any help you can give me.

In adults the pneumococcus bacterium cause 70% of the pneumonia cases. In a random sample of n=84 adults who have pneumonia, let X equal the number whose pneumonia was caused by the pneumococcus bacterium. Use the normal distribution to find, approximately, $\displaystyle P(X \le 52)$