Title: Leaving Seattle

Problem: A train is 50 miles from Seattle. It is traveling away from Seattle at a speed of 60 miles per hour. In how many hours will the train be 290 miles from Seattle?  Show your work.

Math Topic/Concept: Solving linear equations.

Materials: None

Classroom Use: (Introductory/Developmental/Evaluation)

Classroom use comments: Use as a introduction to linear equations.

Grade: 9

Grade Cluster: (EarlyElem/LateElem/MS-Jr.High/EarlyHS/LateHS)

Illinois Goal: 8.D.4

Standard: Algebra

Applied? (1-4): 3

Source: Algebra I - Cliff's Quick Review 

Answer: It will take the train four hours to be 290 miles from Seattle.

Strategies Listed: Figure out the question being asked; Draw a picture; Figure knowns and unknowns; Set up an linear equation.

Solution: Question? In how many hours will the train be 290 miles from Seattle?
Knowns are:
50 miles from Seattle 
60 miles per hour
290 miles
Equation:
Let h stand for the number of hours. Then 60h is the distance traveled in h hours,and 60h + 50 is the distance from Seattle in h hours. So 60h + 50 = 290.
Computation:
60h + 50 = 290
- 50 -50
60h = 240
60h = 240
h = 4
Put answer in sentence:
It will take the train four hours to be 290 miles from Seattle.
Check to see if answer is reasonable.
At 60 miles per hour, in four hours the train will travel 240 miles. Since it is starting 50 miles from Seattle, the total would be 290 miles.

Other solution methods (if any):

Extensions or related problems: How long will it take a bus traveling 72 km/hr to go 36 kms? 
Formula: d=rt
36km = (72km/hr)(t)
36 = 72t
.5= t
Therefore, it will take one-half hour for the bus to travel 36 km at 72 km/hr.

Intended rubric or assessment method: rubric
0 - students left question blank
1 - response was incorrect and no explanation
2 - response was correct but little or no work OR the response was incorrect but had work shown directly related to the problem.
3 - correct response with organized work to solution

Notes (if any):

Write-up submitted by: Tammy Belshaw, Carthage, Illinois 

James R. Olsen, Western Illinois University
E-mail: jr-olsen@wiu.edu
updated: December 16, 2001