What is the probability that at least 1 odd number was recorded during the three drawings?

Question

A box contains four numbered balls: 2, 6, 7. and 8. A ball is drawn at random from the box, its number is noted, and it is then returned to the box. This process is repeated two more times. What is the probability that at least 1 odd number was recorded during the three drawings?

Answer 1

Let find probability Pr(all numbers are even) = 1/2·1/2·1/2 = 1/8

then Pr(at least one number odd) = 1 - 1/8 = 7/8