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Question

The sum of two positive numbers is 27 and their product is 170. The positive difference between them is:

This question was previously asked in
RRB NTPC 2025 Under Graduate CBT 1 Question Paper PDF (20-Jun-2026) (Shift 3)
The correct answer is

7

Let the two numbers be \(a\) and \(b\), with \(a + b = 27\) and \(ab = 170\).

Use the identity \((a - b)^2 = (a + b)^2 - 4ab\).

Substitute the values: \((a - b)^2 = 27^2 - 4 \times 170 = 729 - 680 = 49\).

Take the square root: \(a - b = \sqrt{49} = 7\).

As a check, the numbers are 10 and 17, whose sum is 27 and product is 170.

Hence, the positive difference between the two numbers is 7.

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