a large snowplow can clear a parking lot in 6h. A small snowplow needs more time to clear the lot. working together, they can clear the lot in 4h. how long would it take the small snowplow to clear the lot by itself?

Question

a large snowplow can clear a parking lot in 6h. A small snowplow needs  more time to clear the lot. working together, they can clear the lot in 4h. how long would it take the small snowplow to clear the lot by itself?

anonymous · Answer

consider the area the large snowplow clears in one hour to be "x" and the area the small snowplow clears in one hour to be "y" and the area to be cleared "z". after that you have to use some equations. first, you have 6x = z and 4(x+y) = z. substituting gives 6x = 4x+4y.
taking away 4x from both sides, you see that 2x=4y. this means that the large snowplow takes half the time to clear the same area as the small snowplow. this means that the small snowplow would take 12 hrs to finish clearing the plot. answer = 12 hrs.

anonymous · Answer

thanks :)