Posted by **Rilee** on Friday, November 30, 2012 at 9:56pm.

A boat travels 1 km upstream and 1 km back. The time for the round trip is 4 hours. The speed of the stream is 5 km/hr. What is the speed of the boat in still water?

- Math -
**Reiny**, Friday, November 30, 2012 at 10:44pm
let speed of boat be x mph

time upstream = 1/(x-5)

time downstream = 1/(x+5)

1/(x-5) + 1/(x+5) = 4

multiply each term by (x+5)(x-5)

x+5 + x-5 = 4(x^2 - 25)

2x = 4x^2 - 100

4x^2 - 2x - 100 = 0

x = (2 ± √1604)/8

x = 5.256 or x = a negative, which would make no sense

the speed of the boat in still water is appr 5.26 mph

## Answer this Question

## Related Questions

- math - a boat travels 4 km upstream and 4 km back. the time for the round trip ...
- UPSTREAM - THIS EXURSION WITH A BOAT TRAVEL 35KM UPSTREAM AND THEN BACK AGAIN IN...
- math - A boat travels 8km upstream and back in 2 hours. If the current flows at ...
- math (speed) - A boat cruises downstream for 2 hours before heading back. It ...
- math - A boat cruises downstream for 2 hours before heading back. It takes 3.5 ...
- Math - Boat travels 10 mi upstream and 10 mi downstream the stream is moving ...
- Algebra - Boat travels 10 mi upstream and 10 mi downstream the stream is moving ...
- math 0312 - The current in a stream moves at a speed of 9 mph. A boat travels 17...
- Math (urgent) hw due tommorow! - The speed of a stream is 3 km/h. A boat travels...
- math - The speed of a boat in still water is 8 km/h. It travels 60 km upstream ...

More Related Questions