Teacher: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'.
Teacher: Now, understand the problem? Solve this instance: Problem: a large tanker can be filled by two pipes a and b in 30 and 15 hours respectively . how many hours will it take to fill the tanker from empty state if a and b fill it together ?
Options: a ) 8 hr , b ) 10 hr , c ) 12 hr , d ) 9 hr , e ) 5 hr
Student:
b