Aptitude - Problems on H.C.F and L.C.M
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OverviewExercise"Example is better than precept."
- (Proverb)
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| 16. |
The H.C.F. of two numbers is 11 and their L.C.M. is 7700. If one of the numbers is 275, then the other is:
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Answer: Option A
Explanation:
| Other number = |
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11 x 7700 |
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= 308. |
| 275 |
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| 17. |
What will be the least number which when doubled will be exactly divisible by 12, 18, 21 and 30 ?
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Answer: Option A
Explanation:
L.C.M. of 12, 18, 21 30 2 | 12 - 18 - 21 - 30
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= 2 x 3 x 2 x 3 x 7 x 5 = 1260. 3 | 6 - 9 - 21 - 15
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Required number = (1260 ÷ 2) | 2 - 3 - 7 - 5
= 630.
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| 18. |
The ratio of two numbers is 3 : 4 and their H.C.F. is 4. Their L.C.M. is:
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Answer: Option E
Explanation:
Let the numbers be 3x and 4x. Then, their H.C.F. = x. So, x = 4.
So, the numbers 12 and 16.
L.C.M. of 12 and 16 = 48.
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| 19. |
The smallest number which when diminished by 7, is divisible 12, 16, 18, 21 and 28 is:
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Answer: Option C
Explanation:
Required number = (L.C.M. of 12,16, 18, 21, 28) + 7
= 1008 + 7
= 1015
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| 20. |
252 can be expressed as a product of primes as:
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2 x 2 x 3 x 3 x 7 | B. |
2 x 2 x 2 x 3 x 7 | | C. |
3 x 3 x 3 x 3 x 7 | D. |
2 x 3 x 3 x 3 x 7 |
Answer: Option D
Explanation:
Clearly, 252 = 2 x 2 x 3 x 3 x 7.
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