Numbers problems
- 1. Direction: What should come in the place of question mark (?) in the following number series? 24, 25, ?, 41, -8, 73
Options- A. 13
- B. 16
- C. 25
- D. 43 Also asked in: AIEEE, Bank Exams, GATE
Correct Answer: 16
Explanation:
The pattern followed is
- 2. There is a three digit number. The digit at the tenth place is 3. If the place of all the digits are replaced with each other symmetrically about the tens position,then the new number obtained is 396 more than the original three digit number. The sum of the digits at unit & hundredth place is 14. Find out the original number?
Options- A. 513
- B. 539
- C. 439
- D. 613 Discuss
Correct Answer: 539
Explanation:
Ans.
Let digit = xyz
Given y = 3
According to the question = (100z+10y+x) - (100x+10y+z) = 396x99z-99x = 396
Z-x = 4
Also, Z+ x = 14
Solving (i) & (ii)
Z = 9 , x= 5
The original number is 539
- 3. There are four consecutive even integers. Sum of the reciprocals of the first two number is (11/60). Find the reciprocal of third largest number of the series.
Options- A. 1/12
- B. 2/14
- C. 1/14
- D. 2/13 Also asked in: AIEEE, Bank Exams, GATE
Correct Answer: 1/14
Explanation:
Ans. C.
Let 4 consecutive even numbers are x, x+ 2, x+ 4, x+ 6
According to the question -
1/x + 1/x+2 = 11/60
x+2+x/ x(x+2) = 11/60
2(x+1)/x^2 + 2x = 11/60
120x + 120 = 11x 2 + 22x
11x 2 - 98x ? 120 = 0
So ,
X = -24/22 , 10
X = -12/11 , 10
So, the numbers will be 10,12,14,16.
Hence,
Third largest number = 14
Reciprocal of third number = 1/14
- 4. What will come in place of the question mark (?) in the following number series? 3240, 540, 108, 27, ?, 4.5
Options- A. 7
- B. 10
- C. 9
- D. 8 Also asked in: AIEEE, Bank Exams, GATE
Correct Answer: 9
Explanation:
Ans.
540 = 3240/6
108 = 540/5
27 = 108/4
? = 27/3, i.e. ? = 9
- 5. What will come in place of the question mark in the series below? 3, 5, 15, 45, 113, ?
Options- A. 250
- B. 243
- C. 247
- D. 261 Also asked in: AIEEE, Bank Exams, GATE
Correct Answer: 243
Explanation:
Ans.
5 = 3 + (13 + 1)
15 = 5 + (23 + 2)
45 = 15 + (33 + 3)
113 = 45 + (43 + 4)
? = 113 + (53 + 5), i.e. ? = 243
- 6. What will come in place of the question mark in the series below? 2, 17, 89, 359, 1079, ?
Options- A. 2137
- B. 2121
- C. 2377
- D. 2159 Also asked in: AIEEE, Bank Exams, GATE
Correct Answer: 2159
Explanation:
Ans.
17 = 2 x 6 + 5
89 = 17 x 5 + 4
359 = 89 x 4 + 3
1079 = 359 x 3 + 2
? = 1079 x 2 + 1, i.e. ? = 2159
- 7. Which of the following will yield a reclining decimal?
Options- A. 6024
- B. 3024
- C. 9024
- D. 12024 Discuss
Correct Answer: 9024
- 8. How many numbers are there from 300 to 650 which are completely divisible by both 5 and 7?
Options- A. 8
- B. 9
- C. 10
- D. 12 Also asked in: AIEEE, Bank Exams, CAT
Correct Answer: 10
- 9. Find two natural numbers whose sum is 85 andtheleast common multiple is 102.
Options- A. 30 & 55
- B. 17 & 68
- C. 35& 55
- D. 51 & 34 Also asked in: Bank Exams
Correct Answer: 51 & 34
Explanation:
Let a + b = 85?b = 85 ?a
LCM(a,b) =102?ab = 102
k?a(85 ?a) = 102k, where k is a natural number.
- 10. The sum of two numbers is equal to thrice their difference. If the smaller of the numbers is 10 find the other number.
Options- A. 15
- B. 30
- C. 40
- D. None of these Also asked in: Bank Exams
Correct Answer: None of these
Explanation:
Let larger number be x and smaller number be y.
Also, y = 10
According to question,
?(x + y) = 3((x ?y)?(x + 10) = 3(x ?10)
?2x = 40?x = 20
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