NDA 2022 Maths · Mathematics · Sequences and Series · medium

Two harmonic means are inserted between 1/2 and 1/14. The first harmonic mean is

Single correct option

Two harmonic means are inserted between

\dfrac12

and

\dfrac1{14}

. The first harmonic mean is

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Answer: (A) $\dfrac16$

Reciprocals

2,\,x,\,y,\,14

form an AP with

d=\frac{14-2}{3}=4

, giving

6

and

10

. The harmonic means are

\frac16

and

\frac1{10}

, so the first is

\frac16

. Always return from reciprocals.

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