question_answer

Two pipes A and B can fill a tank in 30 min and 36 min respectively. Both pipes are open in the empty tank but due to dust material present in the pipes A flows \[\frac{5}{6}\] of original quantity and pipe B flows \[\frac{9}{10}\] parts of original quantity. After some time pipe is cleaned, then tank is filled in the \[\frac{31}{2}\] min so after how much time pipes are ready to fill the tank properly?                                                            

A) 1 min

B) 2 min

C) 1.5 min

D) 5 min

E) 5.5 min