In: Operations Management
A retired couple supplement their income by making fruit pies,
which they sell to a local grocery store. During the month of
September, they produce apple and grape pies. The apple pies are
sold for $1.55 to the grocer, and the grape pies are sold for
$1.20. The couple is able to sell all of the pies they produce
owing to their high quality. They use fresh ingredients. Flour and
sugar are purchased once each month. For the month of September,
they have 1,240 cups of sugar and 1,890 cups of flour. Each apple
pie requires 1½ cups of sugar and 3 cups of flour, and each grape
pie requires 2 cups of sugar and 3 cups of flour.
a. Determine the number of grape and the number of
apple pies that will maximize revenues if the couple working
together can make an apple pie in 7 minutes and a grape pie in 4
minutes. Together, they plan to work no more than 55 hours.
(Round your answers to nearest whole number. Omit the "$"
sign in your response.)
Apple | Pieces | |
Grape | Pieces | |
Revenue | $ | |
b. Determine the amounts of sugar, flour, and time
that will be unused. (Leave no cells blank - be certain to
enter "0" wherever required. Round your intermediate calculations
and final answers to the nearest whole number.)
Sugar | cups | |
Flour | cups | |
Time | minutes | |
LP Model:
a) |
||||
fruit pies |
price |
flour |
sugar |
time (min) |
apple pies |
$1.55 |
3 |
1.5 |
7 |
grape pies |
$1.20 |
3 |
2 |
4 |
max. availability |
1890 |
1240 |
3300 |
|
Decision variables: Let a,g be the number of pies made in September |
||||
objective function: |
||||
maximize revenue |
||||
revenue = 1.55a+1.20g |
||||
constraints: |
||||
a,g>=0,int |
non-negativity |
|||
3a+3g<=1890 |
flour availability |
|||
1.5a+2g<=1240 |
sugar availability |
|||
7a+4g<=3300 |
time availability |
model in Excel:
solver solution:
a) |
||
Apple |
260 |
Pieces |
Grape |
370 |
Pieces |
Revenue |
847 |
|
b) |
||
Sugar |
110 |
cups |
Flour |
0 |
cups |
Time |
0 |
minutes |