You jog along a straight trail at 15 km/h. Then you rest for 1 hour and jog back home on that trail at 18 km/h. If you were gone from home for 3 h, how far away from home did you go?

Question

Please explain how to do problems similar to this, formulas examples etc.

Answer 1

It starts with writing an equation that ties together the information you are given.

In this case, you are given the total time, so it makes sense to write an equation for time.

The basic formula that applies is distance (d) = velocity (v) * time (t). (d = v * t). Since our equation will be for time, we will use t = d / v.

Set up the basic equation for time:

total time = time out + time of rest + time for return

Replace each time with an expression based on what is known. Make sure the units are consistent---in this case hours and kilometers, and velocity in km / hour

3 = d / 15 + 1 + d / 18

rearrange and simplify:

d / 15 + d / 18 = 2

6 * d = 5 * d = 180 (both sides multiplied be the least common multiple which is 90)

11 * d = 180

d = 16.36