SOLUTION: An 150-unit apartment complex currently collects $90,000 per month in rent. Rent on each apartment is $600. The new management company wants to increase revenues to $113,400. But f

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equation Customizable Word Problems -> SOLUTION: An 150-unit apartment complex currently collects $90,000 per month in rent. Rent on each apartment is $600. The new management company wants to increase revenues to $113,400. But f      Log On


   



Question 1154160: An 150-unit apartment complex currently collects $90,000 per month in rent. Rent on each apartment is $600. The new management company wants to increase revenues to $113,400. But for each $25 increase, two tenants will move out. How many rent increases will be needed to produce revenue of $113,400?
Found 2 solutions by ikleyn, josmiceli:
Answer by ikleyn(52754) About Me  (Show Source):
You can put this solution on YOUR website!
.

From the condition, when the rent price is  600 + 25i, where i is the number of the 25-dollar increments,

the number of units occupied is 

    N(i) = 150 - 2i.


So, the revenue is  R(i) = (600+25i)*N(i) = (600+25i)*(150-2i).



We want to find " i " in a way to get  R(i) = 113400.


It gives you an equation

    (600+25i)*(150-2i) = 113400.


Simplify and solve for " i "


     90000 + 3750i - 1200i - 50i^2 = 113400

     50i^2 - 2550i + 23400 = 0

       i^2 - 51i + 468 = 0

     i%5B1%2C2%5D = %2851+%2B-+sqrt%2851%5E2-4%2A468%29%29%2F2 = %2851+%2B-+27%29%2F2.


Case 1.  i = %2851-27%29%2F2 =  12.


         It means 12 increments by 25 dollars each; so, the new price is 600+12*25 = 900 dollars.

     

Case 2.  i = %2851%2B27%29%2F2 =  39.


         It means 39 increments by 25 dollars each; so, the new price is 600+39*25 = 1575 dollars.


ANSWER.  There are two answers,  900 dollars and  1575 dollars.

Solved.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +n+ = the number of $25 increases in rent
I assume that 1 tenant moving out means 1 apartment
becoming vacant
------------------------------
[ total monthly rent ] = [ rent/apt + increase ] x [ decreased number of apps ]
+113400+=+%28+600+%2B+25n+%29%2A%28+150+-+2n+%29+
+113400+=+90000+%2B+3750n+-+1200n+-+50n%5E2+
divide both sides by +50+
+2268+=+1800+%2B+75n+-+24n+-+n%5E2+
+-n%5E2+%2B+51n+-+468+=+0+
+n+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
+n+=+%28-51+%2B-+sqrt%28+51%5E2-4%2A%28-1%29%2A%28-468%29+%29%29%2F%282%2A%28-1%29%29+
+n+=+%28-51+%2B-+sqrt%28+2601+-+1872+%29%29%2F%28%28-2%29%29+
+n+=+%28-51+%2B-+sqrt%28+729+%29%29%2F%28%28-2%29%29+
+n+=+%28+-51+%2B+27+%29+%2F+%28-2%29+
+n+=+%28-24%29%2F%28-2%29+
+n+=+12+
The other answer is:
+n+=+%28+-51+-+27+%29+%2F+%28-2%29+
+n+=+%28-78%29+%2F+%28-2%29+
+n+=+39+
---------------
+113400+=+%28+600+%2B+25n+%29%2A%28+150+-+2n+%29+
+113400+=+%28+600+%2B+25%2A12+%29%2A%28+150+-+2%2A12+%29+
+113400+=+%28+600+%2B+300+%29%2A%28+150+-+24+%29+
+113400+=+900%2A126+
+113400+=+113400+
and
+113400+=+%28+600+%2B+25n+%29%2A%28+150+-+2n+%29+
+113400+=+%28+600+%2B+25%2A39+%29%2A%28+150+-+2%2A39+%29+
+113400+=+%28+600+%2B+975+%29%2A%28+150+-+78+%29+
+113400+=+1575%2A72+
+113400+=+113400+
-----------------------------
Either 12 or 39 rent increases will produce
a revenue of $113,400
( depends of whether they want +2n+=+24+ empty apts
or +2n+=+78+ empty apts )
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Get a 2nd opinion if needed