Word problem

Question

The engine of a small rocket burns 140,000 lb of fuel in 1 min. At this rate, how many pounds of fuel does the rocket burn in 45 s?

Answer 1

We have a consistent unit of force lb, but the unit for time is not consistent. 

 

Use this conversion factor:

 

1 min = 60 sec

 

 

Now we can set a proportion.

 

Ratio of pounds = ratio of time

 

 

140000 / x = 60 / 45

 

140000 / x = 4 / 3

 

where x is amount of fuel in pounds the rocket burns in 45 s.

 

 

Cross multiply.

 

4x = 420000

 x = 105000

 

 

The rocket burns 105000 pounds of fuel in 45 sec.