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In an examination a student has to answe...

In an examination a student has to answer 4 questions out of 5 questions; questions 1 and 2 are however compulsory. Determine the number f ways n which the student can make the choice.

Text Solution

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It is given that 2 questions are compulsory out of 5 questions.
So, these two questions are always included in the selection.
We know that, the selection of n distinct objects taken r at a time in which p objects are always included in `""^(n-p)C_(r - p)` ways.
`therefore` Total number of ways `= ""^(5-2)C_(4-2) = ""^(3)C_(2)`
`= (3"!")/(2"!"1"!") = (3 xx 2"!")/(2"!") = 3`
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