Lesson 4-8 Rate-timeDistance Problems
D = rt
D=distance r= speed t= time
• 1. At noon a private plane left Austin for
Los Angeles, 2100 Km away, flying at 500
km/h. One hour later a jet left Los Angeles
for Austin at 700 km/h. At what time did
they pass each other?
Rate
time
Distance
Plane
500
t
500t
Jet
700
t - 1
700(t-1)
2100
• 500t + 700(t – 1)=2100
• 500t + 700t – 700= 2100
•
+700=+700
• 1200t
• 1200
= 1400
1200
• t= 1h and 20 minute
• At noon 12 + 1= 13 and 20 minute
• Or 1:20 P.M
• At 8:00 A.M. the Smiths left a campground, driving
at 48 mi/h. At 8:20 A.M the Garcias left the same
campground and followed the same route, driving
at 60 mi/h. At what time did they overtake the
Smiths?
Rate
Time
Distance
Smiths
48 mi/h
t
48t
Garcias
60 mi/h
T–1
3
60(t +1)
3
• 48 t = 60( t - 1/3)
• 48t = 60t - 20
• 12t = 20
t= 50 minute
• The Smiths overtake at 8:50