Q22 of 64 Page 122

A bag contains six white marbles and five red marbles. Find the number of ways in which four marbles can be drawn from the bag if

(a) they can be of any colour


(b) two must be white and two red and


(c) they must all be of the same colour.

Formula:- (i)nCr


Given:-number of white marbles =6, number of red marbles =5


number of marbles = 6 white + 5 red = 11 marbles


(A)If they can be of any colour


Then we have to select 4 marbles out of 11
∴ Required number of ways


=11C4


(b)Number of ways of choosing two white and two white and two red are


=6C2x5C2



=15x10


=150


(c) If they all must be of same colour,
Four white marbles out of 6 can be selected


=6C4
And 4 red marbles out of 5 can be selected


=5C4
∴ Required number of ways


6C4+5C4=15+5=20


More from this chapter

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