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

Question

anonymous · Answer

This is a fun problem.   You start by realizing that you have 7 bills.

anonymous · Answer

yes.

anonymous · Answer

Am I seeing things or did the # of one dollar bills go from 1 to 3?  Did you happen to change the problem?  It's ok if you did.  Otherwise I didn't catch it correctly the first time.  It looks like you have 9 bills.

anonymous · Answer

no its three 1 dollar bills, four 5 dollar bills and two 10 dollar bills

anonymous · Answer

maybe you had them mixed up

anonymous · Answer

The probability of getting a 10 dollar bill first is 2/9.  The events are not independent, so you take into account that after selecting a bill, you have only 8 bills left, of which there are still 3 one-dollar bills.  The probability of selecting a one-dollar bill at this point is 3/8.  So now, you just multiply the probs and simplify the fraction.  Then you're done!

anonymous · Answer

ok hold on and you can check my answer

anonymous · Answer

is it 1/12

anonymous · Answer

I probably di just look at it too fast the first time, but I caught it in time.  Happens when you are helping several people at once!  Yes!  you got it right!  Good job!

anonymous · Answer

thanks so much

anonymous · Answer

and yea its happened to me