Compare the ratio of 1 car to 60 minutes to x cars in 1 minute.
B
b
Compare the ratio of 1 car to 60 minutes to x cars in x minutes.
C
c
Compare the ratio of 1 car to 80 minutes to x cars in 1 minute.
D
d
Compare the ratio of 1 car to 80 minutes to x cars in x minutes.
E
e
The combined rate will be the average of each of the individual rates.
F
f
Solve the equation from Part E for x.
A
a
1/60
B
b
x/60
C
c
1/80
D
d
x/80
E
e
x/60+x/80=1
F
f
about 34.3 min
Practice makes perfect
a
Kendal can wax 1 car in 60 minutes. Therefore in one minute, or 160 of this time, she can wax 160 cars.
b
Kendal can wax 1 car in 60 minutes. Therefore in x minutes, or x60 of this time, she can wax x60 cars.
c
Chandi can wax 1 car in 80 minutes. Therefore in one minute, or 180 of this time, she can wax 180 cars.
d
Chandi can wax 1 car in 80 minutes. Therefore in x minutes, or x80 of this time, she can wax x80 cars.
e
We are given how long it takes Kendal to wax a car alone, and how long it takes Chandi to wax a car alone. We need to determine the combined rate when Kendal and Chandi work on the car together. The fractions representing the individual rates will total to 1.
x/60+x/80=1
f
In order to determine the combined rate, we will solve the equation from Part E for x.
