Harmonic mean of a series is the reciprocal of the arithmetic mean of the reciprocal of the values of its items.

**Calculation of Harmonic Mean (H.M.) **:

Harmonic Mean is** used in the following cases :- **

- For determining average speed or velocity.

- To find out average price.

- If the item given in the question which is variable is to be kept as constant in the answer, or vice versa, then harmonic mean will be calculated.