Chapter 8 linear appliCaTionS 287
Let t represent the number of hours the second car has traveled after pass-
ing the intersection.
drt
t
t
t
=
=
=
=
10 5
10
5
2
It will take the second car 2 hours to overtake the first.
PRACTICE
- Lori starts jogging from a certain point and runs 5 mph. Jeffrey jogs
from the same point 15 minutes later at a rate of 8 mph. How long will
it take Jeffrey to catch up to Lori? - A truck driving east at 50 mph passes a certain mile marker. A motorcy-
clist also driving east passes that same mile marker 45 minutes later. If
the motorcyclist is driving 65 mph, how long will it take for the motor-
cyclist to pass the truck?
✔SOLUTIONS
- Lori has jogged
rt=d
(^5) ()^1560 =^54
miles before Jeffrey began. Jeffrey is catching up to Lori at the rate of
8 – 5 = 3 mph. How long will it take someone traveling 3 mph to cover
(^54) miles?
Let t represent the number of hours Jeffrey jogs.
3 5
4
1
3
5
4
5
12
t
t
t
=⋅
Jeffrey will catch up to Lori in 125 hours or () 125 () 60 = 25 minutes.
PRACTICE
- Lori starts jogging from a certain point and runs 5 mph. Jeffrey jogs