Sunday

February 1, 2015

February 1, 2015

Posted by **Lucas** on Tuesday, October 16, 2007 at 8:47pm.

thank you

- Math -
**PsyDAG**, Wednesday, October 17, 2007 at 10:22amLet x = speed of A and x + 80 = speed of B.

Speed = distance/time. therefore

Distance = speed * time

Distance traveled by A + distance traveled by B = 3200

This should help you solve your problem. Thanks for asking.

- Math -
**tchrwill**, Wednesday, October 17, 2007 at 12:56pmSubjects

Art

Business

Computers

English

Foreign Languages

Health

Home Economics

Mathematics

Music

Physical Education

Science

Social Studies

Features

Contribute

Download

Experts

Forum

Job Openings

Homework Tips

Libraries.Jiskha

Link to Us

Reference

School Supplies

Search

Homework Help Forum: Math

Current Questions | Post a New Question | Answer this Question | Further Reading

Posted by Lucas on Tuesday, October 16, 2007 at 8:47pm.

Train A and train B leave station going in opposite directions. Train B leaves 1/2 later than train A. Train B travels 80km/h faster than Train A. In 2 hours the trains are 3200KMs apart. How fast is each train traveling..

thank you

The answer depends on whether the total elapsed time is 2 hours or 2.5 hours.

The statement "In 2 hours, the trains are 3200km apart" could mean 2 hours total elapsed time including the 1/2 hour head start of train A before train B departs or 2 hours of elapsed time "after" train A traveled 1/2 hour.

Let V = the speed of train A

Let V + 80 = the speed of train B

Assuming that the total travel time of both trains is 2 hours:

1--Train A travels distance d = .5V in 1/2 hour.

2--The travel time of train B is (3200 - .5V)/(2V + 80) = 1.5 hours

3--3200 - .5V = 3V + 120

4--3.5V = 3080 making V = 880 km/hr.

5--Train B's speed is therefore 960km/hr.

Check:

Train A travels 440km in the first 1/2 hour.

This results in 2760km between the two trains when train B departs.

They are seperating from one another at the combined speed of 880 + 960 = 1840KM/HR.

The time required for them to be 3200km apart at the end of 2 hours is t = 2760/1840 = 1.5 hours.

Total elapsed time is 1/2 + 1.5 = 2 hours.

**Answer this Question**

**Related Questions**

pre algebra - train A leaves a station at 1:15 PM,traveling 60 mph.Train B ...

algebra - Train A leaves a station traveling at 80km/h. Two hours later, train B...

algebra - train A and B are traveling in the same direction on parallel tracks. ...

Algebra 2 (Distance Problem) - A train leaves Union Station for Central Station...

physics - An express subway train passes through an underground station. It ...

physics - An express subway train passes through an underground station. It ...

college physics - An express subway train passes through an underground station...

algerba - Train A & B are traveling in the same direction on parelle tracks....

algebra - tains A and train B are travling in the same dicrtion on a parral ...

Math Word Problem - A metra commuter train leaves Union Station in Chicago at 12...