<PRE><B>Question 223211</B>
A boat can maintain a speed of 16mph. 
The boat makes a trip upstream in 20 mins.
 The return trip takes 15 minutes. What is the speed of the current?
:
Change min to hrs:
15 min = 15/60 = 1/4 hr
20 min = 20/60 = 1/3 hr
:
Let c = speed of the current
then we can say:
(16 - c) = boat speed up stream
and
(16 + c) = boat speed down stream
:
The distance up and the distance back are equal. Write a distance equation
Dist = time * speed
;
Up dist = down dist
{{{1/3}}}(16-c) = {{{1/4}}}(16+c)
Multiply both sides by 12 to get rid of those denominators
4(16-c) = 3(16+c)
64 - 4c = 48 + 3c
64 - 48 = 3c + 4c 
16 = 7c
c = {{{16/7}}}
c = 2.2587 mph speed of the current
:
:
We can confirm this solution by finding the distance of each, should be equal
.25(16 + 2.2587) = 4.57 miles
.33(16 - 2.2587) = 4.57 miles</PRE>