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: if 20 typists can type 48 letters in 20 minutes , then how many letters will 30 typists working at the same rate complete in 1 hour ? 
Options: a ) 63 , b ) 72 , c ) 144 , d ) 216 , e ) 400
answer:
d


question:
Problem: a train 110 meters long completely crosses a 280 meters long bridge in 38 seconds . what is the speed of the train is ? 
Options: a ) 32 , b ) 45 , c ) 40 , d ) 66 , e ) 09
answer:
c


question:
Problem: the population of a bacteria colony doubles every day . if it was started 8 days ago with 3 bacteria and each bacteria lives for 12 days , how large is the colony today ? 
Options: a ) 512 , b ) 768 , c ) 13122 , d ) 2048 , e ) 4096
answer:

c