Suppose the larger pump alone can empty the tank in L hours, and the smaller pump can finish the job in S hours, then each hour the large pump empties 1/L portion of the tank, and the small pump empties 1/S per hour
Working together for three hours, they empty the whole tank, which is 100% of it, so 3/L+3/S=100%=1
Larger pump can empty the tank in 4 hours less than the smaller one, so L=S-4
replace L: 3/(S-4)+3/S=1
Make the denominator the same to solve for:
3S/[S(S-4)] +3(S-4)/[S(S-4)]=1
(3S+3S-12)/[S(S-4)]=1
(3S+3S-12)=[S(S-4)]
S^2-10s+12=0
use the quadratic formula to solve for S
S is about 8.6
The answer is not whole hour.
Okay here we go!
1. I'm a visual person so i would start by drawing circles for the wheels.
o o o o o o o o o o o o o o o o o o o
2. I tried separating them by threes
ooo ooo ooo ooo ooo ooo o
2 By two's
oo oo oo oo oo oo oo oo oo o
3. then i started to count
ooo ooo ooo ooo ooo = 15 and i still had 4 left over
oo oo = 4 and that would equal to 19 wheels!
the answer is: there are 5 trikes and 2 bicycles!!!!!
Hope that helped!
:)
<span><span>1/3</span> * (<span>1/2</span> - 3 <span>3/8</span>) = -<span>2324</span> ≅ -0.9583333</span>
