Question

A bag contains 3 black, 4 white and 2 red balls, all the balls being different. The number of selection of at most 4 balls containing balls of all the
colours is...
​

Answer 1

Step-by-step explanation:

Required number of selection

=

3

C

1

×

4

C

1

×

2

C

1

(

6

C

3

+

6

C

2

+

6

C

1

+

6

C

0

)

=3×4×2(20+15+6+1)

=42(4!)

Answer 2

Answer:

Step-by-step explanation:

Since each selection should have all the three colours, minimum 3 balls one each colour should be selected in3

C  

1

​  

×  

4

C  

1

​  

×  

2

C  

1

​  

 waysMaximum 6 balls are to be selectedMaximum 6 balls are to be selected                                                    =24(1+6+15+20)

                                                   =42×4!