Problem Solving
4-8Rate-Time-Distance Problems
Overview
Use d = rt. Set up using a chart for each traveler and write an equation about total distance or equal times.
Key ideas
- Each row: rate, time, distance.
- Equation often comes from sum or equality of distances.
- Convert units before solving.
Worked examples
Example 1
Problem. Two cars leave the same point traveling opposite directions at 50 and 60 mph. When are they 220 mi apart?
Solution. 50t + 60t = 220 → 110t = 220 → t = 2 h.
Practice
Try each one. Click Show answer when ready.
- 1.
How long for a car at 45 mph to travel 180 mi?
- 2.
Two trains 300 mi apart head toward each other at 60 and 90 mph. When meet?
- 3.
A jet flies 1200 mi in 3 h. Find rate.
Challenge problems
A little tougher — great for test prep. Click Show answer when ready.
- 1.
A car travels 240 miles in 4 hours. How far will it travel in 7 hours at the same speed?
- 2.
Two trains leave stations 300 miles apart and travel toward each other at 60 mph and 40 mph. When do they meet?