Question

a car can reach a certain place in 12 hours at the speed of 60 km per hour by how much should the speed be increased so that it completes the journey in 10 hours

Answer 1

Dear Student,
Solution)

It is given that a car can reach a certain place in 12 hrs at 60 km/h.
Let the increased speed of car be x km/h so that it can reach the place in 10 hrs.
​​​​​​

speed (km/h)	60	x
time (hrs)	12	10

As,speed of car varies inversely with the time taken,
so
12 × 60 = 10 × x

⇒x = (12×60)/10

​​​​​​⇒x = 72
Therefore, increased speed of car = 72 km/h.

Now, car has to increase its speed by (72-60) km/h = 12 km/h in order to reach the place in 10 hrs.
Regards!