Question

The mean mass of four women is 60 kg.

Answer 1

$Mean\;Mass\;of\;Four\;Women = \frac{Sum\;of\;Masses\;of\;Four\;Women}{4}$

Given Mean Mass of Four Women = 60

$\implies \frac{Sum\;of\;Masses\;of\;Four\;Women}{4} = 60\\ \\\implies Sum\;of\;Masses\;of\;Four\;Women = 60\times4 = 240$

Given the Mass of Fifth Woman = 70 kg

$Mean\;Mass\;of\;Five\;Women = \frac{(Sum\;of\;Masses\;of\;Four\;Women) + (Mass\;of\;Fifth\;Woman)}{5}$

$\implies Mean\;Mass\;of\;Five\;Women = \frac{240 + 70}{5} = \frac{310}{5} = 62\;Kg$

Answer 2

Okay so, 60 x 4 = 240

240 + 70 = 310

310 / 5 = Mean of 62