Question

I like really need help!
you have six $1 bills, two $10 bills, and four $20 bills in your wallet. You select a bill at random. Without replacing the bill, you choose a second bill. what is P($1, then $10)?
(A)77/190
(B)3/100
(C)3/95
(D)2/5

Answer 1

You should construct a probability tree in order to answer your quest :)

Answer 2

How many total bills do you have? How many of these are $1 bills?
\[P($1)=\frac{\text{number of }$1}{\text{total number of bills}}\]
How many bills are left when you remove the 1$ bill? How many of these $10 bills?
\[P($1,\text{ then }$10)=P($1)\times\frac{\text{number of }$10}{\text{total number of bills}-1}\]