instruction:
In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
question:
Problem: a man can row a distance of 5 km in 60 min with the help of the tide . the direction of the tide reverses with the same speed . now he travels a further 30 km in 10 hours . how much time he would have saved if the direction of tide has not changed ? 
Options: a ) 2 , b ) 8 , c ) 4 , d ) 6 , e ) 5
answer:
c


question:
Problem: a man can row downstream at 16 kmph and upstream at 10 kmph . find the speed of the man in still water and the speed of stream respectively ? 
Options: a ) 3 , b ) 5 , c ) 6 , d ) 4 , e ) 9
answer:
a


question:
Problem: a sprinter starts running on a circular path of radius r metres . her average speed ( in metres / minute ) is π r during the first 30 seconds , π r / 2 during next one minute , π r / 4 during next 2 minutes , π r / 8 during next 4 minutes , and so on . what is the ratio of the time taken for the nth round to that for the previous round ? 
Options: a ) 4 , b ) 8 , c ) 16 , d ) 32 , e ) 36
answer:

c