Question 205607
Cindy and Dave left the dock to canoe downstream. Fifteen minutes later Tammy
 left by motorboat with the supplies.
Since the motorboat traveled twice as fast as the canoe, it caught up with the
 canoe 3km from the dock. 
What was the speed of the motorboat?
;
Speed will be in km/hr; change 15 min to .25 hrs
:
Let s = the motor boat speed
then
.5s = speed of the canoe)
:
Write time equation: (time = {{{dist/speed}}}
:
Motor time + 15 min = Canoe time
{{{3/s}}} + .25 = {{{3/(.5s)}}}
Multiply equation by s, results
3 + .25s = 2(3)
;
3 + .25s = 6
:
.25s = 6 - 3
s = {{{3/.25}}}
s = 12 km/h motorboat speed
:
:
Check solution, find the travel times
3/6 = .5 hrs
3/12= .25 hrs
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diff = .25 hrs (15 min)