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'.

Q: Problem: 28 machines can do a work in 10 days . how many machines are needed to complete the work in 40 days ? 
Options: a ) 10 , b ) 6 , c ) 4 , d ) 7 , e ) 5

A: d
****
Q: Problem: a 250 meter long train crosses a man standing on the platform in 12 sec . what is the speed of the train ? 
Options: a ) 228 , b ) 108 , c ) 1266 , d ) 75 , e ) 211

A: d
****
Q: Problem: a man rows his boat 95 km downstream and 60 km upstream , taking 2 hours each time . find the speed of the stream ? 
Options: a ) 76 kmph , b ) 6 kmph , c ) 9 kmph , d ) 8 kmph , e ) 4 kmph

A:
c
****