A bag contain 8 red and 5 white balls. Three balls are drawn at random. Find the probability that: (i)All the three balls are white. (ii)All the three balls are red. (iii)One ball is red and two balls are white.

Explanation

Total number of balls` = 8 + 5 = 13`

Total number of events for drawing 3 balls `=13_(c_3)`

(i) Total number of events for getting white balls `=5_(c_3)`

P(all 3 balls white)
`=>(5_(c_3)/13_(c_3))`

`=>((5!)/((3!)(2!)))/((13!)/((3!)(10!)))`

`=>((5!)/(13!))xx(((3!)(10!))/((3!)(2!)))`

`=>(5xx4xx3)/(13xx12xx11)`

`=>(5)/(143)`

...