SOLUTION: A river has a current of 5 mph. It takes Bob half an hour longer to paddle upstream 1.2 miles than to paddle downstream the same distance. What is Bob's rate in still water?

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Question 1054219: A river has a current of 5 mph. It takes Bob half an hour longer to paddle upstream 1.2 miles than to paddle downstream the same distance. What is Bob's rate in still water?
Found 3 solutions by josgarithmetic, jorel555, MathTherapy:
Answer by josgarithmetic(39618) About Me  (Show Source):
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            SPEED        TIME        DISTANCE
UPSTR        r-5         t+0.5        1.2
DOWNST       r+5          t           1.2


system%28%28r-5%29%28t%2B1%2F2%29=1.2%2C%28r%2B5%29%2At=1.2%29

Answer by jorel555(1290) About Me  (Show Source):
You can put this solution on YOUR website!
Let p be the rate at which Bob paddles. Then:
1.2/(p+5)+ 1/2=1.2/(p-5)
2.4(p-5)+(p-5)(p+5)=2.4(p+5)
12p-60+5pē-125=12p+60
5pē-245=0
pē-49=0
(p+7)(p-7)=0
p=7,-7
Throwing out the negative result, we get Bob's padding speed in still water to be 7 mph. ☺☺☺☺

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

A river has a current of 5 mph. It takes Bob half an hour longer to paddle upstream 1.2 miles than to paddle downstream the same distance. What is Bob's rate in still water?
With the rate in still water being S, solve the following TIME equation: 1.2%2F%28S+-+5%29+=+1.2%2F%28S+%2B+5%29+%2B+1%2F2 to find S.