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 21 lines are drawn in a plane such that no two of them are parallel and no three are concurrent , then in how many points do they intersect ? 
Options: a ) 150 , b ) 170 , c ) 190 , d ) 210 , e ) 230

Answer: d


Question: Problem: in a 500 m race , the ratio of the speeds of two contestants a and b is 3 : 4 . a has a start of 155 m . then , a wins by : 
Options: a ) 60 m , b ) 20 m , c ) 40 m , d ) 20 m , e ) 23 m

Answer: c


Question: Problem: dan can do a job alone in 12 hours . annie , working alone , can do the same job in just 9 hours . if dan works alone for 4 hours and then stops , how many hours will it take annie , working alone , to complete the job ? 
Options: a ) 2 , b ) 4 , c ) 6 , d ) 8 , e ) 10

Answer:
c