Problema Solution
A speedboat takes 3 hours longer to go 60 miles up a river than to return. If the boat cruises at 15 miles per hour in still water, what is the rate of the current?
Answer provided by our tutors
Let x= Rate of the current.
When the boat goes downstream, it goes along with the current, so its speed is 15+x miles per hour.
When the boat goes upstream, it goes against the current, so its speed is 15-x miles per hour.
Let's form an equation from the given information above.
60/15-x=60/15+x+3
(60)/15-x-(60)/15+x=3
equation simplifies to:
x^2+40x-225=0
x=5 miles per hour.