The Gateway to Computer Science Excellence
+1 vote
70 views

A box contains six red balls and four green balls. Four balls are selected at random from the box. What is the probability that two of the selected balls are red and two are green ?

  1. $\large\frac{3}{7}$
  2. $\large\frac{4}{7}$
  3. $\large\frac{5}{7}$
  4. $\large\frac{6}{7}$

UGCNET-Dec2007-II-1

in Probability by Veteran
recategorized by | 70 views

1 Answer

+1 vote
$4$  balls can be chosen from  $10$  balls in   $^{10}C_4$ ways. (Total number of ways)

The desirable(favourable) case is choosing $2$ red balls from $6$ red balls and choosing $2$ green balls from $4$ green balls.

So the required probability would be:  $\frac{^{6}C_2\times ^{4}C_2}{^{10}C_4}$  $=$  $\frac{3}{7}$

Option A is correct.
by Active
Quick search syntax
tags tag:apple
author user:martin
title title:apple
content content:apple
exclude -tag:apple
force match +apple
views views:100
score score:10
answers answers:2
is accepted isaccepted:true
is closed isclosed:true
52,217 questions
59,926 answers
201,116 comments
118,162 users