SOLUTION: When 15 is appended to a list of integers, the mean is increased by 2. When 1 is appended to the enlarged list, the mean of the enlarged list is decreased by 1. How many integers w

Question 1067722: When 15 is appended to a list of integers, the mean is increased by 2. When 1 is appended to the enlarged list, the mean of the enlarged list is decreased by 1. How many integers were in the original list?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = the number of integers in the original list
Let = the mean of the original list
------------------------
Originally, the total, , of the integers was:

--------------------
Add to the list
(1)
--------------------------------------
Add to the enlarged list
(2)
--------------------------------------
(1)
(1)
(1)
and
(2)
(2)
(2)
-----------------------
Multiply both sides of (2) by
and subtract (1) from (2)
(2)
(1)
------------------------

and
(1)
(1)
(1)
(1)
-----------------------------------------
There were 4 integers in the original list
-----------------------------------------
check:
(1)
(1)
(1)
--------------------
(1)
(1)
(1)
(1)
and
(2)
(2)
(2)
(2)
OK

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