An integer $x$, satisfying $10 \leq x \leq 99$, is to be chosen. The probability that at least one d

Question

An integer $x$, satisfying $10 \leq x \leq 99$, is to be chosen. The probability that at least one digit of $x$ is 7

Professor PC Thomas Classes · Answer

Total numbers = 90. Numbers without 7 are $8 	imes 9 = 72$. With 7: $90 - 72 = 18$. Prob = $18/90 = 1/5$.