Poisson process question: In a certain game, there is two type of player can join, group player or individual player.

A group of player come in to join the game at a rate of 10 per hour, the group can be consist of 1 to 4 people with probability 0.1, 0.5, 0.2, 0.2 respectively,

individual player come in to join the game at a rate of 5 per hour

1. What is the expectation and variance of the number of player joining the game in a certain hour?