shakunthala devi puzzles Bird and the train:

The distance between Station Atena and Station Barcena is 90 miles. A
train starts from Atena towards Barcena. A bird starts at the same time
from Barcena straight towards the moving train. On reaching the train,
it instantaneously turns back and returns to Barcena. The bird makes
these journeys from Barcena to the train and back to Barcena continuously
till the train reaches Barcena. The bird finally returns to Barcena and
rests. Calculate the total distance in miles the bird travels in the
following two cases:
(a) the bird flies at 90 miles per hour and the speed of the train is
60 miles per hour
there is no need to consider their meeting pt at all.the train has
been running for 90miles/(60miles/hr)=1.5hrs.bird flies till train reaches
destination frm strting pt.so bird flies for1.5hrs at the vel
given(90).so dist=1.5*90=135miles
(b) the bird flies at 60 miles per hour and the speed of the train is
90 miles per hour
time of train=1hr.so dist of bird=60*1=60miles