Questions

The Teesta River is a 309 km long river flowing through the Indian states of West Bengal and Sikkim, before going to Bay of Bengal through Bangladesh.

Our solution:

Toss the coin twice.
Let TH, HT and TT correspond to the three choices.
And if you get HH, just repeat (so it takes 8/3 tosses on average).


BIASED COIN

If the coin was biased, TH and HT would occur with equal probability.
So you could assign THHT, HTTH and THTH to the three choices, with other 4-toss outcomes rejected.
Or you could assign HTT, THT and TTH to the three choices, with other 3-toss outcomes rejected.

Doing more work in less time, results in an increase in power to do a work.

Controlled railroad crossing includes warning signs, red lights and railway gates, whereas absence of all of these warning signs like red lights and gates includes uncontrolled railroad crossings. 

China flicked the switch on the world’s largest floating solar energy plant.  The massive waterborne plant is expected to generate 40 megawatts at one time and could supply electricity for over 15,000 homes. The pioneering project, located in eastern China, is thought to cement China’s status as a top producer of solar energy in the world.  The plant has been built in Huainan city, Anhui Province, by Sungrow Power Supply, a Chinese company specialised in renewable energy.

Although it is less accurate than adding up individual costs from the WBS, it is less time consuming. The trade-off is accuracy. Answer A is incorrect because to do a more accurate cost estimate, you need to delve into details. Answer C is tempting also, and possible, except we don't really know if the project in question can use perametric modeling . Answer D is incorrect because it takes the most time, but it is most accurate.