The sum of two positive numbers is 240 and their HCF is 15. Find the number of pairs of numbers satisfying the given condition.

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SSC CGL Tier 2 Quant Previous Paper 3 (Held On: 18 November 2020)
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  1. 8
  2. 2
  3. 4
  4. 5

Answer (Detailed Solution Below)

Option 3 : 4
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Detailed Solution

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Given: 

The sum of two number positive number is 240 and their HCF is 15.

Calculation: 

Let two positive number is 15x and 15y where x and y should be coprime that means x and y should have HCH as 1.

According to the question

The sum of the number is 

⇒ 15x + 15y = 240

⇒ x + y = 16

Now, we have to find the number of pair in which sum of the two number is 16 but no common factor between them, such pair is

⇒ (1, 15) (3, 13) (5, 11) (7, 9)

∴ Total possible pairs is 4.

Confusion Points

We can't take (2, 14), (4, 12), (6, 10), (8, 8) Because In these cases the pair should be co-prime.

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