SOLUTION: Sally Sethness assembles stereo equipment for resale in her shop. She offers two products, turntables and cassette players. She makes a profit of $10 on each turntable $6 on each c

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Question 1058154: Sally Sethness assembles stereo equipment for resale in her shop. She offers two products, turntables and cassette players. She makes a profit of $10 on each turntable $6 on each cassette. Both must go through two steps in her shop - assembly and bench checking. A turntable take 12 hours to assemble and 4 hours to bench check. A cassette player take 4 hours assemble and 8 hours to bench check. Looking at this month's schedule, Sally sees that she has 60 assembly hours uncommitted and 40 hours of bench-checking time available. Find her best combinations of turntables and cassette player. What is the total profit on the combination you found?
Found 2 solutions by ewatrrr, ikleyn:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
12t + 4c = 60 assemble
4t + 8c = 40 benchcheck
|Divide 2nd EQ by -2 to eliminate c
12t + 4c = 60
-2t - 4c = -20
10t = 40
t = 4 and c = 3
| 4($10) + 3($6) = $58

Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
.
Sally Sethness assembles stereo equipment for resale in her shop.
She offers two products, turntables and cassette players.
She makes a profit of $10 on each turntable and $6 on each cassette.
Both must go through two steps in her shop—assembly and bench checking.
A turntable takes 12 hours to assemble and 4 hours to bench check.
A cassette player takes 4 hours to assemble but 8 hours to bench check.
Looking at this month's schedule, Sally sees that she has 60 assembly hours uncommitted
and 40 hours of bench-checking time available.
Use graphic linear programming to find her best combination of turntables and cassette players.
What is the total profit on the combination you found?
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Let X be the number of turntable  and Y be the number of cassette players.


We want maximize the profit function

    P(X,Y) = 10X + 6Y


under the following restrictions

    12X + 4Y <= 60      (assembly time)

     4X + 8Y <= 40      (bench check time)

     X >= 0,  Y >= 0


The plot of the feasibility domain is shown in the Figure below.


    


    Plots y = %2860-12x%29%2F4  (red) and y = %2840-4x%29%2F8 (green)



It is a quadrilateral in QI with the vertices  at points P1 = (0,0), P2 = (0,5), P3 = (4,3), P4 = (5,0).


We apply the standard Linear Programming method in its geometric interpretation.


The solution is one of these 4 points, where the objective function (profit) has a maximum.


You calculate the values of the objective function  P(X,Y)  (profit)  at listed points


    P1:  P(0,0) = 10*0 + 6*0 =    0,

    P2:  P(0,4) = 10*0 + 6*5 =   30,

    P3:  P(4,3) = 10*4 + 6*3 =   58,

    P4:  P(6,0) = 10*5 + 6*0 =   50.


Comparing these values, you find the optimal point.

It is  P3:  (X,Y) = (4,3),  which means  4 turntables and 3 cassette players, providing maximum PROFIT of 58 dollars.

Solved.

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If you want to see many other similar and different solved problems,  look into the lesson
    - Solving minimax problems by the Linear Programming method
in this site.