Question 886388
i believe you are correct.
the correct solutuion appears to be 14.44444444...... which is equivalent to 130/9.


their answer of 90/13 doesn't make much sense if i understand the problem correctly.


here's how i solved it.


rate of the slow hose is x.
rate of the fast hose is 2.25x


when they work together, their rates are additive.


you get the equation of:


(x + 2.25x) * 10 = 1


simplify this to get 3.25x * 10 = 1


solve for x to get x = 1/32.5


that's the rate of the slow hose.


the rate of the fast hose is 2.25/32.5


the fast hose, filling the pool on its own, fills at a rate of 2.25/32.5 of the pool in one hour.


the formula becomes:


2.25/32.5 * T = 1


solve for T to get T = 32.5/2.25 = 14.4444444 which convert to a fraction of 130/9.


the websites aren't perfect and errors do crop up from time to time.
you did everything right.