There is 10 a stack of cards, each given a different number 1 from 10 to . Suppose we select a card randomly from the stack, replace it, and then randomly select another card. What is the probability that the first card is an odd number and the second card is less than 4?

Question

There is 10 a stack of  cards, each given a different number 1 from 10 to . Suppose we select a card randomly from the stack, replace it, and then randomly select another card. What is the probability that the first card is an odd number and the second card is less than 4?

oobleck · Answer

there are 5 odd numbers, and 3 cards less than 4, so since the events are independent, the probability of both is 5/10 * 3/10 = 3/20