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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

Question 39 Problems on Simultaneous Linear Equations Exercise 6

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.

Answer:

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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