Question

A store offers some food items at bulk pricing where the price is dependent on the pounds of the item being purchased. The store also offers the same foods at bag pricing where each size prepackaged bag has a set price. The table shows the store’s prices for rice, carrots, and beef.

image


Jordan has
$
15
and will purchase some rice at the bulk prices.

The function
f
(
x
)
represents the amount of money Jordan will have left as a function of the number of pounds,
x
, of rice purchased.

Jordan states that
f
(
3
)
=
5
and
f
(
7
)
=
8
.

Which statement BEST explains the error in Jordan's function notation statements?

A.
f
(
7
)
=
8
is incorrect because Jordan will not have
$
8
remaining after buying
7
pounds of rice.

B.
f
(
7
)
=
8
is incorrect because Jordan will not have
$
7
remaining after buying
8
pounds of rice.

C.
f
(
3
)
=
5
is incorrect because Jordan will not have
$
5
remaining after buying
3
pounds of rice.

D.
f
(
3
)
=
5
is incorrect because Jordan will not have
$
3
remaining after buying
5
pounds of rice.

Answer 1

C

f(x) is the money remaining, so f(3)=15 − (cost of 3 lb). The table shows 3 lb costs $5, so f(3)=10, not 5. Jordan has confused the cost with the amount left (the same error appears for 7 lb).