Question 902075
Candy can boat around the shore of Lake Sawyer in 3 hours and 15 minutes. If she decreases her average speed by 0.5 km/hr then her time increases by 15 minutes. How many kilometers long is the shore of the lake?
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let x=distance around the lake shore
let s=initial speed of boat
(s-.5)=reduced speed of boat 
distance/speed=travel time
..
x/s=3.25 hrs
x/(s-.5)=3.25+.25=3.5
..
x=3.25s
x=3.5(s-.5)=3.5s-1.75
3.25s=3.5s-1.75
.25s=1.75
s=7
x=3.25s=22.75
How many kilometers long is the shore of the lake? 22.75 km