Maths : Basic Numeracy

Q 52 / 370

UPSC CSE Prelims 2025

If 4 ≤ x ≤ 8 and 2 ≤ y ≤ 7, then what is the ratio of maximum value of (x + y) to minimum value of (x − y)?

EXPLANATION

Correct Option (4)

Given the intervals for variables x and y:

  • `4 ≤ x ≤ 8`
  • `2 ≤ y ≤ 7`

To determine the maximum value of `(x + y)`:

  • The maximum value of `x` is 8.
  • The maximum value of `y` is 7.
  • Therefore, the maximum value of `(x + y)` = 8 + 7 = 15.

To determine the minimum value of `(x − y)`:

  • To minimize a difference, the first term (`x`) should be at its minimum, and the second term (`y`) should be at its maximum.
  • The minimum value of `x` is 4.
  • The maximum value of `y` is 7.
  • Therefore, the minimum value of `(x − y)` = 4 − 7 = −3.

The required ratio is the maximum value of `(x + y)` to the minimum value of `(x − y)`:

  • Ratio = `15 / (−3)` = −5.

Since the calculated ratio of −5 is not listed among options 1, 2, or 3, option 4, "None of the above," is the correct answer.

Incorrect Options:

Options 1, 2, and 3 are incorrect because the precisely calculated ratio of the maximum value of `(x + y)` to the minimum value of `(x − y)` is −5. This value does not correspond to 6, `15/2`, or `–15/2`.

Explanation figure for the question: If 4 ≤ x ≤ 8 and 2 ≤ y ≤ 7, then what is the ratio of maximum value of (x + y) to minimum… Explanation figure for the question: If 4 ≤ x ≤ 8 and 2 ≤ y ≤ 7, then what is the ratio of maximum value of (x + y) to minimum…