June 2014



Thwaites Glacier Melting glaciers: A new study by researchers at NASA and the University of California, Irvine, finds a rapidly melting section of the West Antarctic Ice Sheet appears to be in an irreversible state of decline, with nothing to stop the glaciers in this area from melting into the sea. Read more ....

Squid Symbiosis: The small but charismatic Hawaiian bobtail squid is known for its predator-fooling light organ. To survive, the nocturnal cephalopod depends on a symbiotic association with a luminescent bacterium that gives it the ability to mimic moonlight on the surface of the ocean and, in the fashion of a Klingon cloaking device, deceive barracuda and other fish that would happily make a meal of the small creature. Read more ....

Coral reef Protective corals: Coral reefs are widely regarded as one of the most beautiful, diverse and delicate ecosystems on the planet. A new study by an international team of scientists reveals that reefs also play the tough guy role in protecting hundreds of millions of people from rising sea levels and damaging wave action. Read more .....

Sea anemone Oceanic life: A deep-water creature once thought to be one of the world's largest sea anemones, with tentacles reaching more than 6.5 feet long, actually belongs to a new order of animals. Read more ....

Batteries Harnessing waste heat: Vast amounts of excess heat are generated by industrial processes and by electric power plants; researchers around the world have spent decades seeking ways to harness some of this wasted energy. Most such efforts have focused on thermoelectric devices, solid-state materials that can produce electricity from a temperature gradient, but the efficiency of such devices is limited by the availability of materials. Read more ....

Aircraft Brain-controlled flight: Pilots of the future could be able to control their aircraft by merely thinking commands. Scientists of the Technische Universitat Munchen and the TU Berlin claim to have demonstrated the feasibility of flying via brain control - with astonishing accuracy. Read more ....




Solution

Okay. I have to find the time required by the narrow pipe to fill up the tank on its own. Let the time required by it be "t" minutes.

The wide pipe fills up the tank three times faster; it means it requires one-third the time required by the narrow one. Therefore, the wide pipe on its own fills up the tank in t/3 minutes.

Let's get back to the narrow pipe. By the way, let's assume that the tank holds "l" litres of water. The narrow pipe, therefore, takes "t" minutes to fill "l" litres of water. So, in one minute it will fill up l/t litres of water.

The wide pipe takes t/3 minutes to fill "l" litres of water. So, in one minute it will fill l/t/3, that is 3l/t litres of water.

Together the two pipes will fill up l/t + 3l/t litres of water in one minute. This means the two pipes together fill up 4l/t litres of water in one minute. In one minute they fill 4l/t litres of water, so in 40 minutes they, together, fill up 40 x 4l/t litres of water, that is 160l/t litres.

But in 40 minutes they, together, fill up the tank; that is, they fill "l" litres of water in 40 minutes. So, 160l/t = l.

So, 160/t = 1, or t = 160. But "t" is the time required by the narrow pipe to fill up the tank on its own. Therefore, the narrow pipe, on its own, fills up the tank in 160 minutes. Did I get it right or did I make a mistake somewhere?



Some useful links for
your career:


  • Union Public Service Commission - www.upsc.gov.in
  • IIT-Kharagpur - www.iitkgp.ac.in
  • Indian Statistical Institute - www.isical.ac.in
  • Indian Institute of Technology Madras - www.iitm.ac.in
  • Indian Institute of Management, Ahmedabad - www.iimahd.ernet.in
  • Indian Institute of Mass Commission - www.iimc.nic.in
  • IIT Bombay - www.iitb.ac.in
  • Indian School of Mines, Dhanbad - www.ismdhanbad.ac.in
  • Birla Institute of Technology, Ranchi - www.bitmesra.ac.in
  • Central Institute of Fisheries Nautical and Engineering Training - www.cifnet.nic.in
  • Indian Institute of Information Technology, Allahabad (Deemed University) - www.iiita.ac.in
  • Central Marine Fisheries Research Institute, Kochi - www.cmfri.com
  • Tata Institute of Social Sciences, Mumbai - www.tiss.edu

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