(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Another challenging question about probability..............

Originial question:

A factory produces two types of shirt: shirt A and shirt B. Each type of shirt has 3 sizes: small (S), medium (M) and large (L). The number of shirt A produced and the number of shirt B produced are in a ratio 2:3. For each type of shirt, the number of shirts in S, M, L sizes are in the ratio 2:5:3

(a) If a shirt is chosen at random, find the probability that it is shirt A in S size.

(b) If a shirt is chosen at random and found to be size S, find the probability that it is shirt B.

2. Relevant equations

3. The attempt at a solution

(a) (2/5) x (2/10) (my approach is the proportion of shirt A multiply the proportion of small size, i don't know if it's true.)

(b) I think it is a conditional probablilty problem but i am not sure. I can construct the equation. It should be

P(shirt B | size S) = P ( B and S ) / P(S)

then i come into problem , i don't know what P(S) and P(B and S) should be.

Thank you for help.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: I always fear probability

**Physics Forums | Science Articles, Homework Help, Discussion**