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 August 26th, 2018, 10:21 PM #1 Senior Member   Joined: Aug 2014 From: India Posts: 310 Thanks: 1 what is the value of C ? The speed of the boat in still water is 22 kmph. It takes the same time for the boat to travel 1.2 km upstream as it does to travel 32km downstream. What is the speed of the current? Solution: The overall speed of boat going downstream will be speed downstream = 22 + c The overall speed of boat going upstream will be speed of boat MINUS speed of current, because boat and current are pointing in opposite directions. speed upstream = 22 – c The typical equation for distance, rate, and time can be used. distance downstream = rate downstream * time 32 km = (22 + c) * t distance upstream = rate upstream * time 1.2 km = (22 – c) * t It seems almost impossible to answer, since we do not know what t is. But you could solve each equation for t. Then equate the results, because same t value is used in both. 32 km / (22 + c) = t 1.2 km / (22 – c) = t So if both things equal t, they equal each other. 32 km / (22 + c) = 1.2 km / (22 – c) C = 20.4 But C value is 10 kmph. how to solve this problem ?
 August 26th, 2018, 11:21 PM #2 Global Moderator   Joined: Dec 2006 Posts: 19,542 Thanks: 1751 It seems that the 1.2 km given in the problem should have been 12 km. Thanks from topsquark
August 27th, 2018, 02:09 AM   #3
Senior Member

Joined: Aug 2014
From: India

Posts: 310
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Quote:
 Originally Posted by skipjack It seems that the 1.2 km given in the problem should have been 12 km.
why ?

 August 27th, 2018, 04:09 AM #4 Global Moderator   Joined: Dec 2006 Posts: 19,542 Thanks: 1751 Because 12 km would lead to c = 10 km/h.
 August 27th, 2018, 05:13 AM #5 Math Team   Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 13,129 Thanks: 914 c = current speed @22+c..........................32................. ...........>h hours [downstream] @22- c............12...........>h hours [upstream] 32 / (22+c) = 12 / (22-c) Solve for c Thanks from topsquark and Ganesh Ujwal

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