(a)[3]
Show that the probability of getting exactly one head is $0.225$.
(b)[2]
Complete the probability distribution table for $X$, with $x = 0, 1, 2, 3, 4$ and entries such as $P(X = 0) = 0.05$, $P(X = 1) = 0.225$ and $P(X = 4) = 0.075$ already provided.
(c)[2]
Given that $\text{E}(X) = 2.1$, find $\mathrm{Var}(X)$.