Please help me understand how to solve this.

Students in a class take a quiz with eight questions. The number of x questions answered correctly can be approximated by the following probability distribution: P(x) 0.04 0.02 0.05 0.08 0.12 0.23 0.22 0.16 0.08 Find the mean (u) of the probability distribution. Round to the nearest tenth as needed. Find the variance (02) of the probability distribution. Round to the nearest tenth as needed. Find the standard deviation (0') of the probability distribution. Round to the nearest tenth as needed