TASK DEFINITION: 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'.
PROBLEM: Problem: two taps a and b can fill a cistern in 12 minutes and 18 minutes respectively . they are turned on at the same time . if the tap a is turned off after 4 minutes , how long will tap b take to fill the rest of the cistern ? 
Options: a ) 8 min . , b ) 9 min . , c ) 10 min . , d ) 7 min . , e ) none of these

SOLUTION: a

PROBLEM: Problem: a can do a piece of work in 10 days . he works at it for 4 days and then b finishes it in 9 days . in how many days can a and b together finish the work ? 
Options: a ) 6 , b ) 7 , c ) 5 , d ) 4 , e ) 1

SOLUTION: a

PROBLEM: Problem: a and b can do a piece of work in 12 days and 16 days respectively . both work for 3 days and then a goes away . find how long will b take to complete the remaining work ? 
Options: a ) 6 days , b ) 12 days , c ) 15 days , d ) 9 days , e ) 8 days

SOLUTION:
d