You have three $1 bills, four $5 bills, and two $10 bills in your wallet. You select a bill at random. Without replacing the bill, you choose a second bill at random. Find P($5 then $10).

1/12
1/72
2/27
1/9

Question

You have three $1 bills, four $5 bills, and two $10 bills in your wallet. You select a bill at random. Without replacing the bill, you choose a second bill at random. Find P($5 then $10). 
  
1/12
1/72
2/27
1/9

anonymous · Answer

First you have a 4/9 chance of grabbing a $5

Then because you don't replace the bill, instead of having 9 bills, you will have only 8 to choose from. 

Then the chance of getting a $10 would be 2/8

To find the probability of both of these happening in this order, you have to multiply (4/9)*(2/8)
= 1/9

anonymous · Answer

thank you (: