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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?
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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