Uniform Motion Problems Part.2

1. May 7, 2006

Richay

Can somebody double check me on this.

At 5 p.m., Alex rode off from Asteroid. One hour later, Jessica rode off from Asteroid in the opposite direction at a speed 400 kph less than that of Alex. If they were 7900 km apart at 11 p.m., how fast did each travel

Answer in the form: Alex, Jessica

Alex rode off at 5 p.m. at x km
By 11 p.m. (6 hours later), his distance was 6x km

Jessica rode off at 6 p.m. at x-400 km
By 11 p.m. (5 hours later), her distance was: 5(x-400) km

The total distance between them was 7900 km.
6x + 5(x-400)=7900

6 x 900 = 5400 (Alex)

900 - 400= 500 x 5 = 2500 (Jessica)

5400+2500 = 7900

So Alex's speed was 900 and Jessica's was 500

Did i do this correctly? I Know i've posted this problem before but it was in the wrong section. And i solved it the correct way this time i hope...

Last edited: May 8, 2006
2. May 8, 2006

Harmony

The solution is correct.

3. May 8, 2006

Richay

Man my teacher is a stupid.

We had a test on this, My answer is Alex - 900 and Jessica - 500. But he says it's wrong.