Question

127. Ali leaves home for his school at a speed of 12 )
mph. Twenty minutes later his father starts
following him at a rate of 36 mph. How long (in
minutes) will the father take to catch up with Ali?​

Answer 1

Answer:

Step-by-step explanation:12mph=12/60m/min

i.e 0.2m/min

After 20 min,

Distance travelled =0.2×20mitre

=4mitres

Then his father start moving

With speed 36m/h=36/60m/min

=3/5m/min

Let the point they meet be x

And distance between them is 4m

Let the point of father be A and the point of ali be B

Then AB=4m

Ax=Bx+4

Ax/3/5=Bx/1/5

5Ax/3=5Bx

Ax=3Bx

Bx+4=3Bx

4=2Bx

Bx=2

Which implies total distance =4+2=6m

Time =distance/speed

=6/3/5

=2×5

=10min