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: it will take 16 days for mary to complete a certain task alone . she worked for 8 days before she was joined by her sister . both of them completed the remaining task in 2 and half days . if her sister had joined her when she started the task , how many days would it have taken ? 
Options: a ) 6 , b ) 8 , c ) 2 , d ) 5 , e ) 4
[EX A]: d

[EX Q]: Problem: a 21 cm long wire is to be cut into two pieces so that one piece will be 2 / 5 th of the other , how many centimeters will the shorter piece be ? 
Options: a ) 12 , b ) 6 , c ) 88 , d ) 77 , e ) 14
[EX A]: b

[EX Q]: Problem: a 1 k . m . long wire is held by n poles . if one pole is removed , the length of the gap becomes 12 / 3 m . what is the number of poles initially ? 
Options: a ) 500 , b ) 501 , c ) 502 , d ) 503 , e ) 504
[EX A]:
b