5 wht, 3 blk balls in urn; 2 randomly draw. Find prob that

[lovely227]

(this problem contains 3 parts)

An urn contains 5 white balls and 3 black balls. Two balls are drawn at random from this urn. Find the probability that...

a. both balls are white
b. both balls are black
c. 1 ball is white the other is black

I don't know where to start with this one, help would be appreciated

 

[pka]

Re: Probability Question

Suppose an urn contains R red balls and G green balls. Draw two balls out.
The probability that both are red is \(\displaystyle \frac {{R \choose 2}} {{{R+G} \choose 2}}}\).

The probability that both are green is \(\displaystyle \frac {{G \choose 2}} {{{R+G} \choose 2}}}\).

The probability that one red and one green is \(\displaystyle \frac {{R \choose 1}{G \choose 1}} {{{R+G} \choose 2}}}\).

\(\displaystyle {N \choose K} = \frac {N!} {(K!)(N-K)!}\)