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ML Aggarwal Solutions Class 9 Mathematics Solutions for Problems on Simultaneous Linear Equations Exercise 6 in Chapter 6 - Problems on Simultaneous Linear Equations
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A boat sails a distance of 44 km in 4 hours with the current. It takes 4 hours 48 minutes longer
to cover the same distance against the current. Find the speed of the boat in still water and the
speed of the current.
Let’s assume the speed of the boat in still to be x km/hr
And the speed of the current = y km/hr
Speed of the boat in the direction of current = (x + y) km/hr
Speed of the boat against the current = (x - y) km/hr
We know, distance = speed x time
Then according to the given conditions in the problem, we have
44 = (x + y) x 4
x + y = 44/4
x + y = 11 … (i)
And,
x – y = 5 … (ii)
Now, adding equations (i) and (ii) we have
x + y = 11
x – y = 5
2x = 16
x = 16/2
x = 8
On substituting the value of x in (i), we get
8 + y = 11
y = 11 – 8
y = 3
Therefore, the speed of the boat in still water = 8 km/hr and speed of the current = 3 km/hr.
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