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HCF and LCM ( 6 to 10 ):
APTITUDE QUESTIONS (HCF AND LCM):
6. Reduce 128352/238368 to its lowest terms.
A) 3/4
B) 5/13
C) 7/13
D) 9/13
E) None of these
View Answer
Answer: option (C)
Explanation:
7. The sum of two numbers is 512 and their HCF is 32. How many numbers of pairs will satisfy the above condition?
A) 5
B) 4
C) 8
D) 12
E) None of these
View Answer
Answer: option (B)
Explanation:
Let the required numbers be 32a and 32b. Then, 32a + 32b = 512
- 32 (a + b) = 512
- a + b = 512/32
- a + b = 16
Now, co-primes with sum 16 are (1, 15), (3, 13), (5, 11) and (7, 9).
∴ required numbers are (32 * 1, 32 * 15), (32 * 3, 32 * 13), (32 * 5, 32 * 11), (32 * 7, 32 * 9).
The number of such pairs is 4.
8. If the ratio of two numbers is 4:5 and their HCF is 5 than what will be the LCM?
A) 10
B) 25
C) 50
D) 100
E) None of these
View Answer
Answer: option (D)
Explanation:
Let the numbers be 4x and 5x. Then, their HCF is = x.
So, x = 5.
So, the numbers are 20 and 25.
LCM of 20 and 25 = 100
9. Find the lowest common multiple of 24, 36 and 48.
A) 120
B) 240
C) 360
D) 144
E) None of these
View Answer
Answer: option (C)
Explanation:
LCM = 2 * 2 * 2 * 2 * 3 * 3 = 144
10. The product of two numbers is 2028 and their HCF is 13. The number of such pairs is:
A) 6
B) 5
C) 3
D) 2
E) None of these
View Answer
Answer: option (D)
Explanation:
Let the numbers be 13a and 13b. Then, 13a * 13b = 2028
- ab = 2028/169
- ab = 12
The product of two numbers is 12 and its co-prime numbers are (1, 12) and (3, 4)
So, the required numbers are (13 * 1, 13 * 12), (13 * 3, 13 * 4).
So, there are 2 such pairs.