SOLUTION: At a price of $70 for a blender, Home Outfitters will sell 12 in one month. Market research has shown that for every $5 decrease in the price of a blender, they will be able to se

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: At a price of $70 for a blender, Home Outfitters will sell 12 in one month. Market research has shown that for every $5 decrease in the price of a blender, they will be able to se      Log On


   



Question 1203126: At a price of $70 for a blender, Home Outfitters will sell 12 in one month. Market research has shown that for every $5 decrease in the price of a blender, they will be able to sell 3 more each month.
a) Determine the price of a blender that will maximize revenue for the month.
b) Approximately how many blenders will be sold to reach revenue of $1100?

Found 2 solutions by ikleyn, Theo:
Answer by ikleyn(52778) About Me  (Show Source):
You can put this solution on YOUR website!
.
At a price of $70 for a blender, Home Outfitters will sell 12 in one month.
Market research has shown that for every $5 decrease in the price of a blender,
they will be able to sell 3 more each month.
(a) Determine the price of a blender that will maximize revenue for the month.
(b) Approximately how many blenders will be sold to reach revenue of $1100?
~~~~~~~~~~~~~~~~~~~~


                    Solution for (a)


From the given information, we easily derive that 12+3n blenders
can be sold at market at the price 70-5n dollars, where n is "any" integer number,
meaning n steps of $5 decrease the initial price of $70.


Hence, the formula for revenue selling blenders at the price 70-5n dollars is

    R(70-5n) = (70-5n)*(12+3n) dollars.


We want to find the value of the argument 70-5n, which provides the maximum 
to the quadratic function (70-5n)*(12+3n).


For it, notice that the quadratic function (70-5n)*(12+3n), just being decomposed into
the product of linear terms, has the zeroes (= x-intecepts) at

    70%2F5 = 14  and  -12%2F3 = -4.


Thus it has the maximum half-way between the x-intercepts.  This half-way value is 

    n%5Boptimum%5D = %2814+%2B+%28-4%29%29%2F2 = 10%2F2 = 5.


So, to get an optimum price, we need to make 5 steps decreasing the initial price of $70 by $5 each time.


Thus we get the optimum price of 70-5*5 = 70-25 = 45 dollars.
At this price, 12+3n = 12+3*5 = 12+15 = 27 blenders can be solved,
providing the maximum possible revenue of 45*27 = 1215 dollars.


Compare it with the revenue of 12*70 = 840 dollars, corresponding to the initial condition.

Part (a) is solved.


                    Solution for (b)


To answer (b), we should find integer values n that provide the closest values of (70-5n)*(12+3n) to 1100.

To get it, I used MS Excel and prepared this Table below


 n	70-5n	12+3n	 product
                        (70-5n)*(12+3n)
---------------------------------
 1	 65	 15	  975
 2	 60	 18	 1080    <<<---===
 3	 55	 21	 1155
 4	 50	 24	 1200
 5	 45	 27	 1215
 6	 40	 30	 1200
 7	 35	 33	 1155
 8	 30	 36	 1080    <<<---===
 9	 25	 39	  975
10	 20	 42	  840


The desired values of n are n= 2  and  n= 8.


The corresponding prices per blender are        70-5*2 = 60 dollars  or  70-5*8 = 30 dollars  (two possible values).

The corresponding amounts of blenders sold are  12+3*2 = 18          or  12+3*8 = 36          (two possible values).

Solved in full.



Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
revenue = price * quantity sold
when price = 70, quantity = 12 making revenue = 70 * 12 = 840.
when the price decreases by 5 dollars, the quantity sold increased by 3 dollars.
let x equal the number of times the price decreases and the quantity increases.
the equation becomes revenue = (70 - 5x) * (12 + 3x)
when x = 0, revenue = 70 * 12 = 840
when x = 1, revenue = 65 * 15 = 975
when x = 2, revenue = 60 * 18 = 1080
when x = 3, revenue = 55 * 21 = 1155

your revenue equation is y = (70 - 5x) * (12 + 3x).
simpiify to get y = 840 + 150x - 15x^2.
rearrange by descending order of degree to get -15x^2 + 150x + 840.

for the revenue to be equal to 1100, the equaton becomes:
-15x^2 + 150x + 840 = 1100
subtract 1100 from both sides of the equation to get -15x^2 + 150x + 840 -1100 = 0.
combine like terms to get -15x^2 + 150x - 260 = 0.
multiply both sides of the equation by -1 to get 15x^2 - 150x + 260 = 0.
factor the equation to get x = 7.7688746209727 or x = 2.2311253790273.

your original equation is y = -15x^2 + 150x + 840
the general form of this equation is y = ax^2 + bx + c.
y will be maximum when x = -b/(2a) = -150/-30 = 5.
when x = 5, y = -15*5^2 + 150*5 + 840 = 1215.
that's the maximum revenue.
it occurs when the price is 70 - 5*5 = 45 and the number of blenders sold is 12 + 5*3 = 27.
45 * 27 = max revenue of 1215.
this is shown on the graph at the point (5,1215).
the value of x is 5 for the maximum revenue.
this means 5 increments of 5 dollars less for the price and 5 increments of 3 units more for the quantity.

the number of increments is not an integer when you want the revenue to be exactly 1100.
the values of x that allow a revenue of at or above 1100 are 2.2311253790273 <= x <= 7.7688746209727.
if you want to make the increments integer, then you would choose x = 3 to 7.
that would make the revenue greater than 1100.

here are two displays of the graph and one display of the spreadshee i used to make the calculations.







i'll be available to answer any questions you might have.
theo