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If the harmonic mean of 60 and x is 48, then what is the value of x?

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NDA 02/2021: Maths Previous Year paper (Held On 14 Nov 2021)
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  1. 32
  2. 36
  3. 40
  4. 44

Answer (Detailed Solution Below)

Option 3 : 40
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Detailed Solution

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Formula used:

For n terms,  a1, a2, a3, ……., an.

Harmonic mean = 

If b is the Harmonic mean of a and b then 

b = 2ab/(a + b)

Calculation:

Given, The harmonic mean of 60 and x is 48

According to the formula used 

⇒ 120x = 48(x + 60)

⇒120x = 48x + 2880

⇒ 120x - 48x = 2880

⇒ x = 40

∴ The value of x is 40.

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