<PRE><B>Question 72888</B>
he Speed boat could travel at 5 times the speed of the current. Thus, it could travel 300 miles downstream in 2 hours more than it took to travel 150 miles upriver.What was the speed of the boat in still water?
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Let s = speed in still water:
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It says,&quot;boat could travel at 5 times the speed of the current.&quot;
Therefore the current is 1/5 the speed (.2s)
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speed upstream: s - .2 = .8s
speed downstream: s + .2 = 1.2s
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Write a time equations; time = dist/speed:
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Time to 300 mi downstream = time to go 150 mi upstream + 2 hrs
{{{300/(1.2s)}}}  =  {{{150/(.8s)}}} + 2
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Multiply equation by 2.4s, gets rid of the denominator and the decimals:
2(300) = 3(150) + 2(2.4s)
600 = 450 + 4.8s
600 - 450 = 4.8s
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4.8s = 150
s = 150/4.8
s = 31.25 mph in still water
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Check solution: 
Current = .2(31.25) = 6.25 mph
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Speed upstream: 31.25 - 6.25 = 25 mph
Speed downstream: 31.25 + 6.25 = 37.5 mph
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300/37.5 = 8 hrs
150/25.0 = 6 hrs
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difference 2 hrs as stated
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