Ram, a farmer, managed to grow shaped- watermelons inside glass cases of different shapes. The shapes he used were: a perfect cube, hemi-spherical, cuboid, cylindrical along with the normal spherical shaped watermelons. Thickness of the skin was same for all the shapes. Each of the glass cases was so designed that the total volume and the weight of the all the water- melons would be equal irrespective of the shape.
A customer wants to but water-melons for making juice, for which the skin of the water- melon has to be peeled off, and therefore is a waste. Which shape should the customer buy?
Let the volume of watermelon = $$V$$
Total surface area = $$S$$
Thickness of the skin = $$t$$
=> Volume usable for juice = $$V - S t$$
Hence, if total surface area is minimum then usable volume of the watermelon will be max.
For equal volume, sphere has the least surface area.
Ans - (E)
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