A bag contains three red, seven yellow and 5 blue marbles.

If three balls are drawn from the bag simultaneously , fin the probability that:

(a) all balls are of different colours

Question

A bag contains three red, seven yellow and 5 blue marbles.

If three balls are drawn from the bag simultaneously , fin the probability that:

(a) all balls are of different colours

anonymous · Answer

total amount of balls: 15

anonymous · Answer

we need to choose 3 different colors, so, we can do 15 C 3, i believe

anonymous · Answer

15*14*13
---------
3*2*1

anonymous · Answer

well the answer is 3/13

anonymous · Answer

isn't 15c 3 the sample space

zarkon · Answer

no...it is the number of elements in the sample space

anonymous · Answer

yeah i know, we need to find the probability, but im a little rusty on stats, maybe somebody well have pity on me an help me out

zarkon · Answer

$$\frac{{3\choose 1}{7\choose 1}{5\choose 1}}{{15\choose 3}}$$

zarkon · Answer

$$=\frac{3\times7\times5}{455}=\frac{3}{13}$$

anonymous · Answer

oh i see thanks you very much zarkon:)