Please help me understand this better.

Use the probability distribution below to answer Questions #13 - 15. The number of overtime hours worked in one week per employee Hours 0 1 2 3 4 5 6 Probability 0.015 0.093 0.151 0.273 0.210 0.171 0.087 Find the mean (u). Round to the nearest tenth as needed. Find the variance (o2). Round to the nearest tenth as needed. Find the standard deviation (o). Round to the nearest tenth as needed