a boat covers 32km upstream and 36km downstream in 7hours. also it covers 40km upstream and 48km downstream in 9hours. find the speed of the boat in still water and that of stream?
Answers
Answered by
16
Let the speed of the boat in still water = x km/hr
speed of steam = y km/hr
upstream speed =x + y
downstream speed =x - y
So, according to question ---
the eqution will be -
32/x-y + 36/x+y = 7 and
40/x-y + 48/x+y=9
by taking 1/x-y=u and 1/x+y=v
32u+36v=7
40u+48v=9
32u+36v=7*10
40u+48v=9*8
320u+360v=70
320u+384v=72
-24v=-2
hence v=1/12
put value of v in eq
40u+48*1/12=9
40u=9-4
u=5/40
u=1/8
now 1/x-y=1/8 => x-y =8
and 1/x+y=1/12 => x+y = 12
hence x= 10 km/hr and y = 2km/hr.
Similar questions