S1 probability

A discrete random variable X has the probability distribution (see pic attached)

E(X) = 0.95

1) Find the probability that X is greater than E(X)

2) Find a and b


Any help/tips? Cant really understand the first question! Many thanks

For 1) What possibilities do you have for $X>E(X)$ and what is the probability of each possibility occurring?

For 2) Recall that $E(X)=\displaystyle\sum_{i} X_ip_i$.

oh right, so for the first one, i add the probability of x=1 x=2 and x=3 ?

Precisely.

thank you!