Question

Average age of n students who promoted in class viii is y years. Three more students included in class whose age are y-1, y-2 and y+3 years. Find their average age when they promoted in class xth.

Answer 1

Answer:

plzzzz give me brainliest ans and plzzzz follow me

Answer 2

The new average age when promoted in class 10 is (y+2) years.

Step-by-step explanation:

We are given the following in the question:

Average age of n students is class 8 is y years.

$Mean = \displaystyle\frac{\text{Sum of all observations}}{\text{Total number of observation}}$

$Mean =\displaystyle\frac{\sum x_i}{n} = y\\\\\displaystyle\sum x_i = ny$

Three students with age  y-1, y-2 and y+3 are added.

We have to find the average age when they promoted in class 10.

$\displaystyle\sum x_i = (ny + 2n) + (y-1+2) + (y-2+2) + (y+3+2)\\\\\displaystyle\sum x_i = (n+3)y + 2n+6\\\\\displaystyle\sum x_i = (n+3)y + 2(n+3)\\\\Mean =\displaystyle\frac{\displaystyle\sum x_i}{n+3} = \dfrac{ (n+3)y + 2(n+3)}{n+3} = y + 2$

Thus, the new average age when promoted in class 10 is (y+2) years.

#LearnMore

There are 40 boys in class VIII and their average age is 14 years. Also, there  are 35 boys in class IX and their average age is 15 years. Find the average  age of both the classes.

​https://brainly.in/question/9617557