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 can do a work in 15 days and b in 20 days . if they work on it together for 5 days , then the fraction of the work that is left is :
Options: a ) 1 / 3 , b ) 7 / 12 , c ) 5 / 12 , d ) 2 / 3 , e ) 1 / 2
answer:
c

question:
Problem: a can do a work in 24 days and b can do it in 8 days . in how many days a and b can do the work ?
Options: a ) 20 days , b ) 10 days , c ) 6 days , d ) 8 days , e ) 7 days
answer:
c

question:
Problem: a sprinter starts running on a circular path of radius r metres . her average speed ( in metres / minute ) is r during the first 30 seconds , r / 2 during next one minute , r / 4 during next 2 minutes , 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