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Question

Find the mean proportional of 6.5 and 24.

This question was previously asked in
RRB Group D 2025 Question Paper (18-Aug-2026) (Shift 1)
The correct answer is

\(2\sqrt{39}\)

The mean proportional of two positive numbers \(a\) and \(b\) is \(\sqrt{ab}\).

Here \(a = 6.5\) and \(b = 24\), so the mean proportional is \(\sqrt{6.5 \times 24} = \sqrt{156}\).

Factorise inside the root: \(156 = 4 \times 39\), so \(\sqrt{156} = \sqrt{4 \times 39} = 2\sqrt{39}\).

Hence, the mean proportional of 6.5 and 24 is \(2\sqrt{39}\).

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Similar Questions

  1. What will come in place of 'X', and \(X > 0\), in the equation \(\dfrac{X}{125} = \dfrac{5}{X}\)

  2. If 4, 8, x and 12 are in proportion, then what is the mean proportion between (x + 3) and (x + 30)?

  3. What is the mean proportional between \(3 + \sqrt{2}\) and \(12 - \sqrt{32}\)?

  4. Which value is the mean proportional between 18 and 45?

  5. If 7 and 20 are two numbers, what is their mean proportional?

  6. The width of a rectangle is 16 cm. If the length is the mean proportional between 9 cm and 16 cm, find the length of the rectangle.

  7. The mean proportional between two numbers is 42. If one of the numbers is 31, find the other number. (Round to the nearest whole number).

  8. If the mean proportional between two numbers is 12 and one of the numbers is 8, what is the other number?

  9. Find the number which when subtracted from 11 and 67 will give 21 as their mean proportional.


Important Questions from Mean Proportional

  1. When x is subtracted from each of 24, 30, 36 and 46, the numbers so obtained in this order, are in proportion. What is the mean proportional between (2x + 3) and (3x + 2)?

  2. What is the mean proportional of 40 and 90?

  3. The first, third and fourth terms of a proportion are 8, 16 and 6 respectively. What is the second term?

  4. The mean proportional between 0.16 and 0.64 is:

  5. What is the mean proportional between 3 and 27?

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