Permutations & Combinations · NDA previous year questions

2011 7 questions

1. Q212011 · 21 Aug 2011

   There are 4 candidates for the post of a lecturer in Mathematics and one is to be selected by votes of 5 men. What is the number of ways in which the votes can be given?

   1. A.1048
   2. B.1072
   3. C.1024
   4. D.625
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   Answer: C

2. Q222011 · 21 Aug 2011

   What is the value of ${\sum }_{r=1}^n\frac{P(n,r)}{r!}$?

   1. A.$2^n-1$
   2. B.$2^n$
   3. C.$2^{n-1}$
   4. D.$2^n+1$
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   Answer: A

3. Q232011 · 21 Aug 2011

   What are the co-ordinates of the foot of the perpendicular from the point $(2,3)$ on the line $x+y-11=0$?

   1. A.$(2,9)$
   2. B.$(5,6)$
   3. C.$(-5,6)$
   4. D.$(6,5)$
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   Answer: B

4. Q402011 · 17 Apr 2011

   In how many ways can 6 girls be seated in 2 empty chairs?

   1. A.10
   2. B.15
   3. C.24
   4. D.30
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   Answer: D

5. Q412011 · 17 Apr 2011

   What is the value of ${\log }_{10}\left(\frac{9}{8}\right)-{\log }_{10}\left(\frac{27}{32}\right)+{\log }_{10}\left(\frac{3}{4}\right)$?

   1. A.3
   2. B.2
   3. C.1
   4. D.0
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   Answer: D

6. Q482011 · 17 Apr 2011

   What is the total number of combinations of $n$ different things taken $1,2,3,\dots ,n$ at a time?

   1. A.$2^{n+1}$
   2. B.$2^{2n+1}$
   3. C.$2^{n-1}$
   4. D.$2^n-1$
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   Answer: D

7. Q562011 · 17 Apr 2011

   5 books are to be chosen from a lot of 10 books. If $m$ is the number of ways of choice when one specified book is always included and $n$ is the number of ways of choice when a specified book is always excluded, then which one of the following is correct?

   1. A.$m>n$
   2. B.$m=n$
   3. C.$m=n-1$
   4. D.$m=n-2$
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   Answer: B