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Question
A student appears in an objective test which contain 5 multiple choice questions. Each question has four choices out of which one correct answer.
How will the answer change if each question may have more than one correct answers?
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Solution
When each question has more than 1 correct answer.
Selecting the correct choice from the 4 choice can be done is
4C1 or 4C2 or 4C3 or 4C4 ways.
4C1 = 4 = 4C3
4C1 = `(4 xx 3)/(2 xx 1)` = 6
4C4 = 1
∴ 4C1 + 4C2 + 4C3 + 4C4 = 4 + 6 + 4 + 1
= 15
Each question can be answered in 15 ways.
Number of questions = 5
∴ Total number of ways = 155
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