Q.5.     Find the number of ways of selecting 9 balls from 6 red balls, 5 white balls and 5 blue balls if each selection consists of 3 balls of each colour.

Answers (1)
S seema garhwal

There are 6 red balls, 5 white balls and 5 blue balls.

9 balls have to be selected in such a way that consists of 3 balls of each colour.

3 balls are selected from 6 red balls in ^6C_3.

3 balls are selected from 5 white balls in ^5C_3

3 balls are selected from 5 blue balls in ^5C_3.

Hence, by the multiplication principle, the number of ways of selecting 9 balls =^6C_3\times ^5C_3\times ^5C_3

                                                                                                              =\frac{6!}{3!3!}\times \frac{5!}{2!3!}\times \frac{5!}{2!3!}

                                                                                                             =20\times 10\times 10=2000

 

 

 

.

Exams
Articles
Questions