In CAT entrance examination paper there are 3 sections, each containing 5 questions. A candidate has to solve 5, choosing at least one from each section. The number of ways he can choose is
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There are 3 questions in each section... with 5 in each ...
To select 5 questions, at least 1 from each section...
The candidate can select (a,b,c) number of questions from sections (1,2,3).
(a,b,c) can be : (1,1,3), (1,3,1), (3,1,1), (1,2,2), (2,1,2), (1,2,2)
The total number of ways:
= 5C1 * 5C1* 5C3 * 3 + 5C1 * 5C2* 5C2 * 3 = 2250
To select 5 questions, at least 1 from each section...
The candidate can select (a,b,c) number of questions from sections (1,2,3).
(a,b,c) can be : (1,1,3), (1,3,1), (3,1,1), (1,2,2), (2,1,2), (1,2,2)
The total number of ways:
= 5C1 * 5C1* 5C3 * 3 + 5C1 * 5C2* 5C2 * 3 = 2250
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