SOLUTION: a boat on a river can go 4 miles downstream in 1/4 hour, but takes 1/2 hours to return to ts starting point. find the speed of the boat in still water and the speed of the current
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Question 904345: a boat on a river can go 4 miles downstream in 1/4 hour, but takes 1/2 hours to return to ts starting point. find the speed of the boat in still water and the speed of the current Answer by mananth(16946) (Show Source):
Distance against 4 miles distance with 4 miles
t=d/r against current -
4.00 / ( x - y )= 0.50
0.50 ( x - y ) = 0.25
0.50 x - 0.50 y = 4.00 ....................1
4.00 / ( x + y )= 0.25
0.25 ( x + y ) = 4.00
0.25 x + 0.25 y = 4.00 ...............2
Multiply (1) by 0.25
Multiply (2) by 0.50
we get
0.13 x + -0.13 y = 1.00
0.13 x + 0.13 y = 2.00
0.25 x = 3.00
/ 0.25
x = 12.00 mph
plug value of x in (1) y
0.50 x -0.50 y = 4.00
6.00 -0.50 -6.00 = 4.00
-0.50 y = 4.00
-0.50 y = -2.00 mph
y = 4.00
boat speed 12.00 mph
current speed 4.00 mph
