Question

Q 7 : The mean of 10 observations is 25. If one observation namely 25 is excluded, the new mean is *

25

20

28

22

​

Answer 1

$We \: know \:that,$

$\boxed{ \pink{ Mean = \frac{Sum \:of \:the \: observations }{Number \:of \: Observations } }}$

$Given \: the \: mean \: of \: 10 \: Observations$

$is \: 25$

$Sum \: of \: 10 \: Observations = 25 \times 10$

$= 250 \: --(1)$

$If \: one \: Observation \: namely \: 25 \:is$

$excluded , then$

$\blue{Sum \: of \: 9 \: Observations = 250 - 25}$

$\blue{ = 225}$

$\green { Number \:of \: observations = 9}$

$\therefore \red{ New \: mean }$

$= \frac{225}{9}$

$= 45$

Therefore.,

$\red{ New \: mean }\green { = 45}$

•••♪