The tutor contemplates shifting gears from snow shoveling to lawn mowing.

Let’s imagine a lawn 25mx25m, so its area is 625m², and that the mower covers 0.15m² every second. At what second during the procedure will the mower cover 1% or the remaining unmown lawn?

Solution:

Assume the mowing begins at 0s. The remaining unmown lawn at time t is 625 – 0.15t; one percent will be 0.01(625 – 0.15t). Since the mower covers 0.15 m² every second, we have

0.15 = 0.01(625 – 0.15t)

0.15 = 6.25 – 0.0015t

Subtracting 6.25 from both sides gives

-6.1 = -0.0015t

Finally, dividing both sides by -0.0015 yields

4067 = t

At 4067s, 1% of the remaining lawn will be covered that second.

My lawn mower is a push one; it doesn’t have gears:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.