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A small boat took 2 hr to travel Downstream with the four mile per current the return trip against the same current took 3 hours.
Find the speed of the boat in Still water
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The speed downstream is (u+4) miles per hour, where "u" is the boat speed in still water.
The speed upstream is (u-4) miles per hour.
The distance traveled downstream for 2 hours is d = (u+4)*2.
The distance traveled upstream in 3 hours is the same, which gives you an equation
(u+4)*2 = (u-4)*3.
Simplify and solve for "u":
2u + 8 = 3u - 12,
8 + 12 = 3u - 2u,
u = 20.
Answer. The boat speed in still water is 20 miles per hour.
It is a typical and standard Upstream and Downstream round trip word problem.
You can find many similar fully solved problems on upstream and downstream round trips with detailed solutions in lessons
- Wind and Current problems
- More problems on upstream and downstream round trips
- Selected problems from the archive on the boat floating Upstream and Downstream
in this site.
Read them attentively and learn how to solve this type of problems once and for all.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this textbook under the section "Word problems", the topic "Travel and Distance problems".