A mechanic can install carburetors in 3 cars every 4 hours. At that rate, how long will it take the mechanic to install carburetors in 5 cars? a) 6 hr. 20 min. b) 6 hr. 40 min. c) 7 hr. 15 min. d) 7 hr. 30 min. e) 7 hr. 45 min. Hint First you can write a proportion from the information given: 3 cars is to 4 hours as 5 cars is to

x

hours. From this you can write an equation that can be solved for

x

.

B:

6 hours 40 minutes Explanation

From the information given, you can write the proportion 3 cars is to 4 hours as 5 cars is to

x

hours, where

x

represents the number of hours the mechanic will take to install carburetors in 5 cars. This gives

= ,

which simplifies to

3x = (4)(5) = 20.

Therefore,

x =

Since

hour

is 40 minutes,

x is 6 hours 40 minutes. = 6 hours

.