Question

harmonica mean of 10 15 20 30
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Answer 1

Answer:

16.

Step-by-step explanation:

If harmonic mean of four numbers a,b,c,d is x then,

$\frac{1}{x}=\frac{\frac{1}{a} + \frac{1}{b}+\frac{1}{c} +\frac{1}{d} }{4}$.

Given numbers are 10, 15, 20, 30. Let their harmonic mean be x.

Then,

$\frac{1}{x}=\frac{\frac{1}{10} + \frac{1}{15}+\frac{1}{20} +\frac{1}{30} }{4}$

$\frac{1}{x}=\frac{\frac{1}{6}+\frac{1}{12} }{4}$

$\frac{1}{x}=\frac{\frac{3}{12} }{4}$

$\frac{1}{x}=\frac{1}{16}$

x = 16.

Therefore the harmonic 0f 10, 15, 20, 30 is 16.