A train moving at 2 3 rd of its normal speed reaches its destination 20 minutes late Find the normal...........

Explanation:

Let the original speed and time is S and T
then distance = S x T
Now the speed changes to 2/3S and T is T+20
As the distance is same
S x T = 2/3Sx(T+20)
solving this we get t = 40 minutes
=40/60 = 2/3 hour

Hence, option 3 is the correct answer.