A kayaker can paddle 12 mi in 2 h moving with the river current. Paddling at the same pace, the trip back against takes 4 h. Assume that the river current is constant. Find what the kayakers speed would be in still water.

Question

anonymous · Answer

Easy.  If the kayaker paddles 12 mi in 2h he will paddle 24 in 4 hours.

redheadangel · Answer

Yes, but it asked for in STILL water (other than that your reasoning is correct)

anonymous · Answer

I see...

amistre64 · Answer

since the distance is the same each time, equate distance with speed and time

anonymous · Answer

ok do you think you could set it up for me please

amistre64 · Answer

hmm, give me your attempt first.

how are distance speed and time related?

anonymous · Answer

d= R*T

amistre64 · Answer

good,  lets use

distance = speed * time

since the distance is the same we can say:

distance = (river + boat) * time1
distance = (river - boat) * time2

something to that effect

amistre64 · Answer

we have a distance given to us in miles for a time of 2 hours

12miles = (river + boat) * 2 hours

if we assume that the distance is 12 we can compare it with

12miles = (river - boat) * 4 hours

anonymous · Answer

ok I get so like

r+b=6
r-b=3

amistre64 · Answer

good, its a system of eqautions ...

amistre64 · Answer

if we add them as is we eliminate the boat :)

2r = 9  when r=9/2   so we know the river spped

anonymous · Answer

did I set my equation up right

amistre64 · Answer

yeah, you did great

anonymous · Answer

ok give me a sec and tell me if my answers right

anonymous · Answer

ok for r I got 4.5 and b I got 1.5

amistre64 · Answer

my only concern with this thought is that we are not really given an actual distance, just a rate of speed.

if the distance was 12,  then the river is 4.5  and  the boat is 1.5  i agree.

anonymous · Answer

thankyou very much

amistre64 · Answer

youre welcome