APTITUDE Problems On Number and Series

1. 1, 5, 13, 25
  • 85
  • 41
  • 58
  • 47
Explanation : The series is of the form 0^2+1^2, 1^2+2^2,…
2. 1, 8, 9, 64, 25 (Hint : Every successive terms are related)
  • 279
  • 247
  • 216
  • 147
Explanation : 1^2, 2^3, 3^2, 4^3, 5^2, 6^3
3. 5,9,16,29,54,?
  • 258
  • 178
  • 103
  • 155
Explanation : 5*2-1=9; 9*2-2=16; 16*2-3=29; 29*2-4=54; 54*2-5=103
4. 1,2,4,10,16,40,64 (Successive terms are related)
  • 235
  • 258
  • 145
  • 200
Explanation : The series is powers of 2 (2^0,2^1,..). All digits are less than 8. Every second number is in octal number system. 128 should follow 64. 128 base 10 = 200 base 8.
5. A fast typist can type some matter in 2 hours and a slow typist can type the same in 3 hours. If both type combinely, in how much time will they finish?
  • 3 hr 57 min
  • 4 hr 45 min
  • 2 hr 12 min
  • 1 hr 12 min
Explanation : The fast typist’s work done in 1 hr = 1/2 The slow typist’s work done in 1 hr = 1/3 If they work combinely, work done in 1 hr = 1/2+1/3 = 5/6 So, the work will be completed in 6/5 hours. i.e., 1+1/5 hours = 1hr 12 min
6. 6, 24, 60,120, 210 a) 336 b) 366 c) 330 d) 660
  • 660
  • 366
  • 330
  • 336
Explanation : The series is 1.2.3, 2.3.4, 3.4.5, 4.5.6, 5.6.7, ….. ( ‘.’ means product)
7. 0, 5, 8, 17
  • 27
  • 12
  • 24
  • 45
Explanation : 1^2-1, 2^2+1, 3^2-1, 4^2+1, 5^2-1
8. What is the sum of all numbers between 100 and 1000 which are divisible by 14 ?
  • 14258
  • 25586
  • 14585
  • 35392
Explanation : The number closest to 100 which is greater than 100 and divisible by 14 is 112, which is the first term of the series which has to be summed. The number closest to 1000 which is less than 1000 and divisible by 14 is 994, which is the last term of the series. 112 + 126 + …. + 994 = 14(8+9+ … + 71) = 35392
9. If s(a) denotes square root of a, find the value of s(12+s(12+s(12+ …… upto infinity.
  • 3
  • 6
  • 7
  • 4
Explanation : Let x = s(12+s(12+s(12+….. We can write x = s(12+x). i.e., x^2 = 12 + x. Solving this quadratic equation, we get x = -3 or x=4. Sum cannot be -ve and hence sum = 4.
10. 1,4,9,16,25,36,49, ?
  • 56
  • 62
  • 64
  • 47
Explanation : 1,4,9,16,25,36…. All These are square roots of 1,2,3,4,5…… So that the answer is 64(8*8)

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Posted on June 4, 2011, in APTITUDE Problems On Number and Series, Aptitude Quiz Questions with Answers, APTITUDE Test, Quiz. Bookmark the permalink. Leave a comment.

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