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: a constructor estimates that 3 people can paint mr khans house in 4 days . if he uses 4 people instead of 3 , how long will they take to complete the job ? 
Options: a ) 2 , b ) 8 , c ) 1 , d ) 3 , e ) 4

Answer: d


Question: Problem: pipes a and b can fill a tank in 3 and 4 hours . pipe c can empty it in 4 hours . if all pipes are opened together , then the tank will be filled in ? 
Options: a ) 3 hr , b ) 1 / 2 hr , c ) 1 hr , d ) 9 / 7 hr , e ) 5 / 3 hr

Answer: a


Question: Problem: calculate how much time could be saved if the train would run at its usual speed , given that it ran at 4 / 9 of its own speed and got to its destination in 13 hours ? 
Options: a ) 1.22 hrs , b ) 2.22 hrs , c ) 5.22 hrs , d ) 6.22 hrs , e ) 7.22 hrs

Answer:
e