Question

man covered a certain distance at some speed had he moved 3 km/hr faster he would have taken 40 minutes less If he had moved 2 km/hr slower he would have taken 40 minutes more The distance ( in km) 
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Answer 1

Answer:

Let the distance = x km and usual rate = y km/hr Then

y

x

−

y+3

x

=

60

40

⇒

y(y+3)

x(y+3)−xy

=

3

2

⇒

y(y+3)

3x

=

3

2

⇒2y(y+3)=9x...............(i)

and

y−2

x

−

y

x

=

60

40

⇒

y(y−2)

xy−x(y−2)

=

3

2

⇒

y(y−2)

2x

=

3

2

⇒y(y−2)=3x...............(ii)

On dividing eqn (i) by eqn (ii) we get

y−2

2(y+3)

=3⇒2y+6=3y−6⇒y=12

∴ Putting the value of y in (i) we get 2 x 12 x 15 = 9x ⇒ x = 40 km/hr