Question

a student reaches her school in 20 minutes with an average speed of 12km/h.if she wants to reach her school 8 minute earlier,her speed should be ：

Answer 1

her speed should be 30ķm per hour

Answer 2

Answer: Her speed should be 30 km/ hr.

Step-by-step explanation:

First case:

Speed= 12km/ hr

Time= 20 min

This should be converted into hours(hr) as the speed is given in km/hr.

As we know that 60min= 1 hour

Therefore, 20min= (1/60)× 20 = 1/3 hr

Now to find out the distance we use the formula of speed, distance and time.

Distance= Speed × Time

= 12×1/3 km= 4km

Using this distance in the second case as the distance remains the same in both the cases.

Second case:

Speed= ?

Distance= 4km

Time = 8 min

Again converting it into hours in the same way as described above,

Time = 8/60 hr

Now using the formula,

Speed= Distance/Time

= 4/ ( 8/60) km/ hr = 30km/ hr ( Ans).