SOLUTION: A school has 20 teachers, one of them retires at the age of 60 years and a new teacher replaces him, this change reduces the average age of the staff by 2 years, the age of new

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Question 1045433: A school has 20 teachers, one of them retires at the age of 60 years and a new teacher replaces him, this change reduces
the average age of the staff by 2 years, the age of new teacher is:

Found 2 solutions by ikleyn, stanbon:
Answer by ikleyn(52786) About Me  (Show Source):
You can put this solution on YOUR website!
.
A school has 20 teachers, one of them retires at the age of 60 years and a new teacher replaces him, this change reduces
the average age of the staff by 2 years, the age of new teacher is:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You are given

%28S%2B60%29%2F20 - %28S%2Bx%29%2F20 = 2.

Here  S is the sum of ages of 19 teachers and %28S%2B60%29%2F20  is the average age of 20 teachers including the retired one.

%28S%2Bx%29%2F20 is the average age of 20 teachers where the retired teacher's age 60 is replaced by the new teacher's age "x".

Solve for x:

60%2F20+-+x%2F20 = 2,

%2860-x%29%2F20 = 2,

60-x = 2*20 = 40,

x = 60 - 40 = 20.

Answer. The new teacher's age is 20 years.


Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A school has 20 teachers, one of them retires at the age of 60 years and a new teacher replaces him, this change reduces
the average age of the staff by 2 years, the age of new teacher is:
==========================
Original average of the 20 teachers:: "a"
Sum of their ages = 20a
-----------------------
After one retires::
Sum of the 19 teachers ages:: 20a-60
---
Let the new teachers age be "t"
=====
Equation::
original average - new average age = 2 years
a - [20a-60+t]/20 = 2
-----
20a - 20a + 60 - t = 40
t = 20 yrs ( new teacher's age)
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Cheers,
Stan H.
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