More Questions from HCF and LCM

The product of two numbers is 4107. If the H.C.F. of these numbers is 37, what is the greater of the two numbers?

Aptitude HCF and LCM Difficulty: Easy
Choose an option
  • A
    101
  • B
    107
  • C
    111
  • D
    185

Answer

Correct Answer: 111

Explanation

Introduction / Context:This is a direct application of the relationship between the product of two numbers and their highest common factor (H.C.F.) when you are asked to determine the individual numbers. It is a standard type of question in quantitative aptitude, and knowing how to factor correctly is key.

Given Data / Assumptions:

  • The product of the two numbers is 4107.
  • Their H.C.F. is 37.
  • We must find the greater of the two numbers.

Concept / Approach:If two numbers have H.C.F. 37, we can express them as 37a and 37b, where a and b are co-prime positive integers. Then their product is (37a) * (37b) = 37^2 * ab. Since the product is given, we can solve for ab and then find co-prime pairs (a, b) whose product matches this value. This will lead us to the actual numbers, from which we choose the larger.

Step-by-Step Solution:Step 1: Let the numbers be 37a and 37b, with H.C.F.(a, b) = 1.Step 2: Product = 37^2 * ab.Step 3: Given product is 4107, so 37^2 * ab = 4107.Step 4: Calculate 37^2 = 1369.Step 5: So 1369 * ab = 4107.Step 6: Divide to find ab: ab = 4107 / 1369 = 3.Step 7: The co-prime factor pairs of 3 are (1, 3) and (3, 1).Step 8: The corresponding numbers are 37 * 1 = 37 and 37 * 3 = 111.Step 9: Of these, the greater number is 111.

Verification / Alternative check:Check product: 37 * 111 = 4107, which matches the given product.Check H.C.F.: gcd(37, 111) is 37 because 111 = 3 * 37. Both conditions are satisfied, confirming that the numbers are 37 and 111 and the greater one is 111.

Why Other Options Are Wrong:Options a (101), b (107), and d (185) either do not produce the correct product with a compatible partner or do not have H.C.F. 37 with any other integer such that the product is 4107. For example, 101 is prime and 4107 / 101 is not an integer, so it cannot be one of the numbers.

Common Pitfalls:Students may forget to represent the numbers in the form 37a and 37b and instead try random factorizations of 4107. Others may miscalculate 37^2 or the division 4107 / 1369. Writing the steps cleanly and doing the arithmetic carefully makes this question very manageable.

Final Answer:The greater of the two numbers is 111.

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