Elitmus
Exam
Numerical Ability
Arithmetic
In a certain examination paper, there are n questions. For j=1,2....n there are 2^(n-1) students with answer j or more questions wrongly. If total number of wrong answers is 4095 then the value of n is.......?
Read Solution (Total 5)
-
- Let us say there are only 3 questions. Thus there are 2^(3-1)=4 students who have done 1 or more questions wrongly, 2^(3-2)=2 students who have done 2 or more questions wrongly, 2^(3-3)=1 student who had done all three questions wrongly.
Total no. of wrong answer=4+2+1=7=2^3 -1=2^n -1
In our question, Total no. of wrong answer=4095=2^12 -1
then n=12.
Answer, total no. of questions=12 - 10 years agoHelpfull: Yes(13) No(0)
- 2^(n)-1=4095
2^n=4096
2^n=2^12
therefore n=12
- 10 years agoHelpfull: Yes(5) No(4)
- ans is 11 i think .....
- 10 years agoHelpfull: Yes(0) No(1)
- n=12
I think 2^(n)-1 - 10 years agoHelpfull: Yes(0) No(1)
- 2^(n-1)=4095
2^n=4096
so n=12 - 9 years agoHelpfull: Yes(0) No(0)
Elitmus Other Question