An empty barrel is filled with oil at a constant rate that takes 10 hours to fill 6/7 of its capacity. How much more

[Vincen]

An empty barrel is filled with oil at a constant rate that takes 10 hours to fill 6/7 of its capacity. How much more time will it take to finish filling the barrel?

A. 1 hr. 50 mins.
B. 1 hr. 40 mins.
C. 1 hr. 30 mins.
D. 1 hr. 20 mins.
E. 1 hr.

[spoiler]OA=B[/spoiler]

Source: Veritas Prep

[Scott@TargetTestPrep]

An empty barrel is filled with oil at a constant rate that takes 10 hours to fill 6/7 of its capacity. How much more time will it take to finish filling the barrel?

A. 1 hr. 50 mins.
B. 1 hr. 40 mins.
C. 1 hr. 30 mins.
D. 1 hr. 20 mins.
E. 1 hr.

[spoiler]OA=B[/spoiler]

Solution:

The remaining capacity is 1/7 of the barrel. We can use a proportion to determine how much time it will take to finish filling the barrel.

10/(6/7) = x/(1/7)

70/6 = 7x

70 = 42x

70/42 = x

10/6 = x

5/3 = x

So, it takes 1⅔ hours or 1 hour and 40 minutes more to finish filling the barrel.

Answer: B