This is a question from Sheldon Ross,
Let’s start,
P(A person is present) = 0.95
P(A person is absent) = 0.05, these are given in the question.
We must find the probability that everyone who comes will get their seats, but we know that there are only 50 seats and in the worst case 52 0r 51 people will come.
Instead of finding the probability of success, let’s find the probability of failure and subtract it from 1.
p(all 52 will come) =$0.95^{52}$ = 0.069
p(exactly 51 will come) = $\binom{52}{1}$$(0.05)^{1}$$(0.95)^{51}$ = 0.190
->1- (0.069 + 0.1900)
->0.74