Question

The mean of some observations is 10. if a constant 5 is added to each of the observations, then the new mean is ​

Answer 1

Answer:

Step-by-step explanation:

Let x be first no.

And y be second

x+y/2=10

According to the question

((x+5)+(y+5))/2

=(x+y+10)/2

=x+y+5

Hence new mean is also increased by 5

Answer 2

$\fontsize{18}{10}{\textup{\textbf{The new mean is 15.}}}$

Step-by-step explanation:  

Let the number of observations be 'n' and the sum of these n observations be 'S'.

Then, according to the given information, we have

$\textup{Mean of n observations}=10\\\\\Rightarrow \dfrac{\textup{sum of n observations}}{n}=10\\\\\Rightarrow \dfrac{S}{n}=10~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(i)$

When we add 5 to each of these n observations, then the sum becomes

$S'=S+5+5+~.~.~.~+\textup{to n terms}=S+5n.$

Therefore, new mean is given by

$m\\\\=\dfrac{S'}{n}\\\\=\dfrac{S+5n}{n}\\\\=\dfrac{S}{n}+5\\\\=10+5~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~[\textup{Using equation (i)}]\\\\=15.$

Thus, the required new mean is 15.

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Question : The mean of 5 observations is 40. the mean of 4 of them is 38. find the 5th observation.

Link : https://brainly.in/question/8154305.