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'.
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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: some persons can do a piece of work in 12 days . two times the number of these people will do half of that work in ? 
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 8

Answer: a


Question: Problem: a is 30 % more efficient than b . how much time will they , working together , take to complete a job which a alone could have done in 23 days ? 
Options: a ) 11 days , b ) 13 days , c ) 20 3 / 17 days , d ) 21 days , e ) none of these

Answer:
b