Question

12 balls, 3 each of the colours red, green, blue
and yellow are put in a box and mixed. If 3
balls are picked at random, without replace-
ment, the probability that all 3 balls are of the
same colour is​

Answer 1

Answer:

let the red balls be r1,r2,r3

similarly blue balls will be b1 b2 b3

green will be g1 g2 g3

yellow will be y1 y2 y3

sample space for experiment is

s={r1,r2,r3,b1, b2, b3, g1, g2, g3, y1 y2 y3}

n(s)=12

let A be the event that 3 balls picked at random are of same colour

A={r1r2r3,b1 b2 b3,g1 g2 g3,y1 y2 y3}

n(A)=4

p(A)=n(A)/n(s)=4/12=1/3

ANS:probablity of 3 balls picked at random are of same colour is 1/3