Time and Distance Calculations for Road Trip from Dallas to Chicago

[taraxrose]

Homework Statement

Jerry Kramer and Elaine are driving from Dallas to Chicago, a distance of 925 mi. Jerry leaves at 7:12 AM and averages 64 mi/h. Kramer leaves at 6:38 AM and averages 71 mi/h. Elaine leaves at 5:55 AM and averages 66 mi/h. Newman departs Chicago heading for Dallas at the same time Kramer leaves at a speed of 75 mi/h.

c. At what time does Jerry pass Newman?
d. What percentage of the trip has Elaine completed at the time Newman has completed 70% of his trip?

Homework Equations

I have no idea, sorry, other than the speed equation maybe that I already used. I have no idea how to answer those questions although I know it should be easy.

The Attempt at a Solution

I know they end up at their destinations at these times:
Newman: 6:58 PM
Kramer: 7:39 PM
Jerry: 9:39 PM
Elaine: 9:04 PM

 

[mfb]

c) Where is Newman when Jerry leaves Dallas? What is their speed difference?

d) If Newman leaves at 6:38 AM and arrives at 6:58 PM, when did he complete 70% of his trip?

Those are questions you should ask yourself to solve problems like that.

 

[CWatters]

You should also ask yourself what variables are the same for Newman when Jerry when they pass.