# Thread: Selecting money from a bag.

1. ## Selecting money from a bag.

A bag contains 5 ten dollar bills, 7 twenty dollar bills, and 6 fifty dollar bills. What is the probability of drawing.

a)
either ten or twenty dollar bill?

b) either twenty or fifty dollar bill?

2. How many possible choices are there?

How many of these are "either ten or twenty dollars"?

How many of these are "either twenty or fifty dollars"?

3. Originally Posted by soni
A bag contains 5 ten dollar bills, 7 twenty dollar bills, and 6 fifty dollar bills. What is the probability of drawing.

a)
either ten or twenty dollar bill?

b) either twenty or fifty dollar bill?
Try drawing a tree diagram first.

4. Originally Posted by mr fantastic
Try drawing a tree diagram first.
I don't think a tree diagram is going to help...

It's not asking for $Pr(10 \cap 20)$, it's asking for $Pr(10 \cup 20)$...

Surely you can just do $\frac{n(10) + n(20)}{n(\varepsilon)}$...

5. Originally Posted by Prove It
I don't think a tree diagram is going to help...

It's not asking for $Pr(10 \cap 20)$, it's asking for $Pr(10 \cup 20)$...

Surely you can just do $\frac{n(10) + n(20)}{n(\varepsilon)}$...
The tree diagram lets the OP visualise the situation. The required probabilities are then easily read from the tree diagram and added together.