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October 21, 2014

October 21, 2014

Posted by **Maybel** on Tuesday, August 19, 2008 at 4:34am.

If Michael's rowing speed in still water is ten times the speed of the current in the river, what distance had Michael covered before he turned his boat around?

- Maths -
**drwls**, Tuesday, August 19, 2008 at 7:27amWhere was Tom when Michael started rowing? He must have been farther upstream at the time. I will assume Tom was one km upstream when Michael started rowing.

Let v = the river speed and V = 10v be Michael's speed in still water.

Michael rows downstream at a land speed v + V = 11 v and upstream at a land speed of V-v = 9 v. Tom travels at speed v (by floating)

Let T be the time they both are on the water between when Michael starts and finishes rowing.

Let t be the time Micheal rows downstream; T-t is the time he rows upstream

v T = 1 km

11 v t = 9 v (T-t)= 9 - 9 vt

20 vt = 9

vt = 0.45 km

So Tom floated 0.45 km while Micheal rowed downstream and 0.55 km while he rowed upstream. Since Micheal rowed downstream 11 times faster than Tom floated, he would have travelled 11*0.45 = 4.95 km in that time

- Maths -
**Anonymous**, Thursday, June 9, 2011 at 3:17pmdfh

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