Question

Four times the downstream speed is 8 more than 15 times the upstream speed. If difference between downstream and upstream speed is 24 km/hr, then what is the ratio of speed in still water to the speed of the current?

Answer 1

4(x+y) = 15(x-y)+8

4x+4y= 15x-15y+8

19y-11x = 8---------(1)

now,

(x+y)-(x-y) = 24

2y = 24

y = 12 -------(2)

putting (2) in (1) we get

19*12 - 8 = 11x

11x = 220

x = 20

required ratio :-

speed in still water : speed of current = 20:12 = 5:3

Answer 2

Answer:

Speed in still water : Speed of current = 20:12 = 5:3

Explanation:

Given: Four times the downstream speed is 8 more than 15 times the upstream speed. If the difference between downstream and upstream speed is 24 km/hr,

To find: Ratio of speed in still water to the speed of the current

Solution:

$4(x+y) = 15(x-y)+8\\\\4x+4y= 15x-15y+8\\\\\19y-11x = 8---(1)$

now,

$(x+y)-(x-y) = 24\\\\2y = 24\\\\y = 12 ---(2)$

putting (2) in (1) we get

$19*12 - 8 = 11x\\\\11x = 220\\\\x = 20$

required ratio:-

Speed in still water : Speed of current = 20:12 = 5:3