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A boat travels 50 miles up the river in the same amount of time it takes to travel 62 miles down the same river.
If the current is 3 miles per hour, what is the speed of the boat in still water?
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Let "u" be the current speed, in miles per hour.
Then your equation is
= . (1)
The left part is the time spent to travel 50 miles up the river.
The left part is the time spent to travel 50 miles up the river.
So, equation (1) is direct translation of the condition into math.
To solve (1), multiply bot sides by (u-3)*(u+3). You will get
50*(u+3) = 62*(u-3),
50u + 150 = 62u - 186,
150 + 186 = 62u - 50u,
336 = 12u, ---> u = = 28.
Answer. The speed of the boat in still water is 28 mph.
Check. Please do check on your own.
You can find similar fully solved similar problems on upstream and downstream round trips with detailed solutions in the 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
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".