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: a courtyard is 25 meter long and 16 meter board is to be paved with bricks of dimensions 20 cm by 10 cm . the total number of bricks required is 
Options: a ) 16000 , b ) 18000 , c ) 20000 , d ) 22000 , e ) 24000

A: c
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Q: Problem: a and b together can do a piece of work in 10 days . b alone can finish it in 20 days . in how many days can a alone finish the work ? 
Options: a ) 20 , b ) 10 , c ) 15 , d ) 5 , e ) 7

A: a
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Q: Problem: working at a constant rate , p can finish a job in 3 hours . q , also working at a constant rate , can finish the same job in 9 hours . if they work together for 2 hours , how many more minutes will it take p to finish the job , working alone at his constant rate ? 
Options: a ) 20 , b ) 30 , c ) 40 , d ) 50 , e ) 60

A:
a
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