Thirty women were examined in a hospital by a doctor and the number of heart beats per minute were recorded and summarised as follows. Find the mean heart beats per minute for these women, choosing a suitable method.

Number of heart beats per minute:	65-68	68-71	71-74	74-77	77-78	80-83	83-86
Number of women:	2	4	3	8	7	4	2

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Given:

Thirty women were examined in a hospital by a doctor and the number of heartbeats per minute was recorded. 

To do:

We have to find the mean heartbeats per minute for the women.

Solution:

Let the assumed mean be $A=75.5$

We know that, Mean $=A+h \times \frac{\sum{f_iu_i}}{\sum{f_i}}$    

Therefore,  

Mean $=75.5+3\times\frac{4}{30}$

$=75.5+\frac{4}{10}$

$=75.5+0.4$

$=75.9$

The mean heartbeats per minute for the women is $75.9$. 

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Updated on: 10-Oct-2022

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