OG11 PS 154 - Views appreciated!

[T_A_M]

Hey guys!
Would like your views on OG11 PS 154.

An empty pool being filled with water at a constant rate takes 8 hours to fill 3/5 of it's capacity. How much more time will it take to finish filling the pool?

Now it is clear this is a rates and work questions, but why, in the rt = w equation, isn’t 8 used as the t variable (8 hrs should denote time). Whereas it is actually the amount of work done.

i.e. the correctly way to build the formula is 3/5 t = 8

Not sure why 8 is work?

[david2008]

So I think the reason they did that is so you could do the calculation in one step. I agree that the most logical way to construct the equation is:

3/5=(8)(r)

Solve for r which equals 3/40

Then plug into:

1=(t)(3/40) and thus total time to fill the pool is (40/3) which you would then subtract 8 from and get 16/3

[Svedankae]

hey,

dont think in formulas... just try to go at it logically:

8 hours equals 60% of the total time.

Total time * 60 % = 8 hours

So,

Total time minus 8 hours = Answer

13.3333 - 8 = 5.3333