Wednesday

April 23, 2014

April 23, 2014

Posted by **Kim** on Sunday, June 1, 2008 at 12:50am.

- algebra -
**drwls**, Sunday, June 1, 2008 at 1:41amThey probably expect you to assume that the boat is using the same power to go through the water in both directions.

Let V be the boat speed relative to the water in both directions. Relative to the shore, its speed is V+5 going downstream and V-5 going upstream.

Let T be the time that it takes to go downstream, in hours. It take T + 2/3 to go upstream. You can write two equations in the two unknowns, V and T.

4 = (V+5) T

4 = (V-5)(T + 2/3)

4 = (V-5)[4/(V+5) + (2/3)]

4(V+5) = 4(V-5) + (2/3)(V^2-25)

40 = (2/3)(V^2-25)

V^2-25 = 60

V^2 = 85

V = 9.22 mph.

Downstream speed = 14.22 mph

Upstream speed = 4.22 mph

Dowstream travel time = 4/14.22

= 0.281 hrs = 16.9 minutes

Upstream travel time = 4/4.22 = 0.948 hr = 56.9 min

**Related Questions**

algebra - 36 Upstream, downstream. Junior’s boat will go 15 miles per hour in ...

algebra - Show a complete solution. Upstream, downstream. Junior’s boat will go ...

Algebra - A boat can travel upstream 14 miles in same it can travel downstream 8...

Math - Steve's boat will go 14 miles per hour in still water. If he can go 13 ...

Intermediate Algebra - in still water, a paddle boat averages 10 miles per hour...

algebra - A boat can travel 114 miles upstream in the same time that it can ...

Math Word Problem - Steve's boat will go 14 miles per hour in still water. If he...

math - River Current A boat can travel 36 miles upstream in the same time that ...

math help please - Solve the problem. A boat can go 33 mph in still water. It ...

algebra - Gone fishing. Debbie traveled by boat 5 miles upstream to fish in her ...