Status: Preparing myself to break the sound( 700 )-barrier!
Affiliations: IFC - Business Edge, Bangladesh Enterprise Institute
Joined: 15 Feb 2011
Location: Dhaka, Bangladesh
Schools: Texas A&M - Mays; PennState - Smeal; Purdue - Krannert; JohnsHopkins - Carey; Vanderbilt - Owen; WakeForest - Babcock; UBC - Sauder
WE 1: Financial Analyst/Financial Management Trainer - BRAC Afghanistan - 13 months
WE 2: Business Proposal Coordinator - MiDS, Inc. (in Kabul, Afghanistan) - 4 Months (did quit the job bcoz of security concerns)
WE 3: Readers For Readers (A Social Impact Generating Organization) - Co-Founder
, given: 136
My shot is for option D.
Here is why:
This problem can be solved as working-together problem. Let's say, C=5 hours and H=6 hours. If both the tubes are open together, the pool will be filled in (5*6)/(5+6)=2.7 hours(apprx.) i.e. T=2.7 hours. This answer gives validity to options I and III. So, D is the shot.
Then, again, let's say, C=1 hours and H=9 hours. If both the tubes are open together, the pool will be filled in (1*9)/(1+9)=0.9 hours i.e. T=0.9 hours. This answer validates the options I and III, once again. Thus, D is the shot.
(though not necessary anymore) In this way, if you take any positive number, whether faction or integer, answer option I and III will be always valid for this question.