Question

A soccer team is selling T‑shirts as a fundraiser. The table shows how the number of T-shirts they can expect to sell depends on x, the price of each T‑shirt.



Expected T-Shirt Sales
Price (dollars) T-shirt sales, dollars
8 800
9 855
10 900
11 935
12 960
13 975
14 980
15 975
16 960




Part A. Which equation describes the relationship between the total number of dollars in T-shirt sales, y, and the price per T-shirt, x?




y
=
−
5
x
2
+
140
x


y
=
−
5
x
2
+
92
x


y
=
−
5
x
2
+
100
x


y
=
−
5
x
2
+
60
x

Answer 1

y = −5x^2 + 140x

Check: for x = 8, y = −5(8^2) + 140(8) = −320 + 1120 = 800 (and for x = 9 gives 855), so this matches the table.