Q. 125.0( 1 Vote )
In an examination, a student to answer 4 questions out of 5 questions; questions 1 and 2 are however compulsory. Determine the number of ways in which the student can make a choice.
Answer :
Given that student have to answer 4 questions from 5 questions.
It is also told that questions 1 and 2 are compulsory.
It is similar to answering the 2 questions out of the remaining 3 questions as 1 and 2 are compulsory.
Let us assume the no. of ways of answering the questions be N.
⇒ N = No. of ways of answering 2 questions from remaining 3 questions.
⇒ N = 3C2
We know that 
,
And also n! = (n)(n – 1)......2.1
⇒ 
⇒ 
⇒ 
⇒ N = 3
∴ The no. of answering the questions is 3.
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