Question

Suppose you write the numbers 1 to 10 on separate index cards. You randomly choose one card, place it back in the set, and then randomly choose another card. What is the probability that the first card you choose is the number 1 or the second card you choose is the number 2?.

Answer 1

1/100

Explanation:

From 1 to 10 there are 10 numbers, so the fraction would be:

# / 10

Since you are putting the cards back into the deck, the denominator will never change.

The chances of getting " 1 " are 1 / 10.

And the chances of getting " 2 " are also 1 / 10

To find the odds of getting one-after-the-other, you multiply these 2 chances.

( 1 / 10 ) x ( 1 / 10 ) = ( 1 / 100 )

There is a 1 / 100 chance that you will draw 1, then 2 if you put the cards back after drawing.