Question

You pick one of 7 cards. Each card has a number on it: 2, 3, 4, 5, 6, 7, 8. Without putting the card back what is the probability of picking an odd number first and an odd number second? Your fraction should be in simplest form.

Answer 1

There are 3 odd cards (3, 5, 7) out of 7. So
P(first odd) = 3/7. Given one odd was picked, 2 odd remain out of 6, so P(second odd | first odd) = 2/6 = 1/3.
Multiply: (3/7) * (1/3) = 1/7.