# Stats, probability

1. Oct 13, 2005

### Dr-NiKoN

1 out of 5 italians speak english. 1 out of 5 people in italy are tourists. 1 out 2 tourists speaks english.

You meet a english-speaking person in italy, what is the probability that this person is italian.

The way I see the "population":

$P(I) = \frac{2}{10}$ are italians who speaks english.

$P(T) = \frac{1}{10}$ are tourists that speaks english.

You have meet someone from P(I) + P(T), what is the probability that this person is italian?

That probability equates to:
2x + 1y = 1 (x => english-speaking italian, y => english speaking tourist)

Where do I go from here?

2. Oct 13, 2005

### mathman

Your P(I) is wrong. It should be 4/5(italians) x 1/5 (speak English).
Net result P(I)=.16, P(T)=.1.