# Thread: How Would You Do This?

1. ## How Would You Do This?

A packet contains stamps from three different countries.
The packet contains 4 Spanish stamps, 10 French stamps and 6 German stamps.
Two stamps are to be removed at random, without replacement.
Calculate the probability that both stamps will be from the same country.

Now what i did is a big tree diagram but this was a very long and complicated way to do it, does anyone know an easier way.

The answer i got was 33/95............is this what you get?

2. I get the same answer as you. I don't see why a tree diagram is necessary. i just considered three separate cases.

1) getting two Spanish stamps $\frac{4}{20} \times \frac{3}{19}$

2) getting two French stamps $\frac{10}{20} \times \frac{9}{19}$

3) getting two German stamps $\frac{6}{20} \times \frac{5}{19}$

Then just added the probabilities together.

$\frac{4}{20} \times \frac{3}{19} + \frac{10}{20} \times \frac{9}{19} + \frac{6}{20} \times \frac{5}{19} = \frac{33}{95}$