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'.

[EX Q]: Problem: in an examination , a student scores 6 marks for every correct answer and loses 1 mark for every wrong answer . if he attempts all 60 questions and secures 280 marks , the no of questions he attempts correctly is : 
Options: a ) a ) 20 , b ) b ) 38 , c ) c ) 90 , d ) d ) 88 , e ) e ) 37
[EX A]: a

[EX Q]: Problem: a water tank is four - fifths full . pipe a can fill a tank in 10 minutes and pipe b can empty it in 6 minutes . if both the pipes are open , how many minutes will it take to empty or fill the tank completely ? 
Options: a ) 6 , b ) 9 , c ) 10 , d ) 12 , e ) 15
[EX A]: d

[EX Q]: Problem: a and b finish the job in 15 days . while a , b and c can finish it in 5 days . c alone will finish the job in 
Options: a ) 4.50 days , b ) 3.50 days , c ) 6.0 days , d ) 7.5 days , e ) 5.50 days
[EX A]:
d