Question

Two trains leave the station at the same time, but are headed in opposite directions. One train travels at 70 mph and the other train travels at 80 mph. After ___ hours the trains will be 600 miles apart.

Answer 1

let the time be x Then the first train will go 70x mi other train will go 80x mi As the are passing through opposite direction. then 70x+80x = 600 or, x = 4

Answer 2

4 hours

Explanation:

Given: Two trains leave the station at the same time, but are headed in opposite directions. One train travels at 70 mph and the other train travels at 80 mph.

To Find: After how many hours the trains will be 600 miles apart

Solution:

Speed of first train =
`70`
`\text{mph}`

Speed of second train =
`80`
`\text{mph}`

As trains are heading in opposite directions,

Relative speed of trains =
`\text{Speed of first train}+\text{Speed of other train}`

=
`150`
`\text{mph}`

Total distance to be travelled =
`600`
`\text{miles}`

Total time taken =
`\frac{\text{Total Distance}}{\text{Relative speed}}`

=
`(600)/(150)`

=
`4`
`\text{hours}`

After 4 hours the trains will be 600 miles apart