Chapter 11 QuaDraTiC appliCaTionS 393- A grocery store sells 4000 gallons of milk per week when the price is
$2.80 per gallon. Customer research indicates that for each $0.10
decrease in the price, 200 more gallons of milk will be sold.
P = __
Q = __ R = __ - A movie theater’s concession stand sells an average of 500 buckets of
popcorn each weekend when the price is $4 per bucket. The manager
knows from experience that for every $0.05 decrease in the price, 20
more buckets of popcorn will be sold each weekend.
P = __
Q = __ R = __ - An automobile repair shop performs 40 oil changes per day when the
price is $30. Industry research indicates that the shop will lose 5 cus-
tomers for each $2 increase in the price.
P = __
Q = __ R = __ - A fast food restaurant sells an average of 250 orders of onion rings each
week when the price is $1.50 per order. The manager believes that for
each $0.05 decrease in the price, 10 more orders will be sold.
P = __
Q = __ R = __ - A shoe store sells a certain athletic shoe for $40 per pair. The store aver-
ages sales of 80 pairs each week. The store owner’s past experience
leads him to believe that for each $2 increase in the price of the shoe,
one less pair would be sold each week.
P = __
Q = __ R = __
✔SOLUTIONS
- Px Qx
Rxx
=+ =−
=+ −400 25 50 2
() 400 25 () 50 2- PxQx
Rxx
=− =+
=− +280010 4000 200
280010 4000 200..
(. .)())- Px Qx
Rxx
=− =+
=− +4005 500 20
4005 500 20.
(.)( )