Two number, both greater than 27, have H.C.F 27 and L.C.M 162. The sum of the…
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Two number, both greater than 27, have H.C.F 27 and L.C.M 162. The sum of the number is
- A.
195
- B.
175
- C.
135
- D.
189
Attempted by 10 students.
Show answer & explanation
Correct answer: C
To find the sum of two numbers given their Highest Common Factor (H.C.F.) and Least Common Multiple (L.C.M.), we can use the following relationship:
Step-by-Step Calculation
1. Understand the Relationship: Any two numbers with an H.C.F. of H can be represented as H × a and H × b, where a and b are co-prime numbers (they have no common factors).
The L.C.M. is then given by H × a × b.
The product of the two numbers is H² × a × b.
2. Apply the given values:
H.C.F. (H) = 27
L.C.M. = 162
Find the product of the co-prime factors (a × b):
L.C.M. = H × a × b
162 = 27 × (a × b)
a × b = 162 / 27 = 6
3. Find the co-prime pairs (a, b) that multiply to 6: The possible pairs for (a, b) are:
(1, 6)
(2, 3)
4. Determine the actual numbers: Since the numbers must be greater than 27:
Pair (1, 6):
Number 1 = 27 × 1 = 27 (Not greater than 27)
Number 2 = 27 × 6 = 162
(This pair is invalid because one number is not greater than 27)
Pair (2, 3):
Number 1 = 27 × 2 = 54 (Greater than 27)
Number 2 = 27 × 3 = 81 (Greater than 27)
(This pair is valid)
5. Calculate the sum:
Sum = 54 + 81 = 135.