Question

a bag contains 10 red, 8 green and 7 blue balls. if two balls are picked at random one after the other without replacement from the bag, what is the probability that: (i) they are of the different colors ? (ii) at least one ball is blue ?

Answer 1

`|\Omega|=25\cdot24=600`

I.

`|A|=10\cdot8+10\cdot7+8\cdot7=80+70+58=208\\\\P(A)=(208)/(600)=(26)/(75)`

II.

`|A|=7\cdot18=126\\\\P(A)=(126)/(600)=(21)/(600)`