238 algebra De mystif ieD
- The volume of a box with a rectangular bottom is given by V = 120h,
where V is the volume in cubic inches and h is the height in inches. If the
volume of the box is to be 1140 cubic inches, what should its height be? - The volume of a certain cylinder with radius 2.8 cm is given by V = 7.84oh,
where h is the height of the cylinder in centimeters. If the volume needs
to be 25.088o cubic centimeters, what does the height need to be? - At what temperature will the Celsius reading be twice as high as the
Fahrenheit reading? - At what temperature will degrees Fahrenheit be twice degrees
Celsius?
✔SOLUTIONS
- (a) Here x = 80, so C = 18 + 0.35x becomes C = 18 + 0.35(80).
C
C
C
=+
=+
=18 03580
18 28
46.()The charge is $46.
(b) The cost is $39, so C = 18 + 0.35x becomes 39 = 18 + 0.35x.
39 18 035
18 18
21 035
21
035
60=+
−−
=
=
=...xx
x
x
Sixty miles were driven.- The profit is $5000, so P = 25x – 8150 becomes 5000 = 25x – 8150.
5000 25 8150
8150 8150
13 150 25
13 150
25
526
=−
++
=
=
=xx
x,
,xx
The company must sell 526 units.