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प्रश्न
If each edge of a cube is increased by 50%, the percentage increase in the surface area is
विकल्प
50%
75%
100%
125%
उत्तर
125%
Let the original edge of the cube be a units.
Then, the original surface area of the cube = 6a2 units
New edge of the cube = 150% of a
`= (150"a")/100`
`= (3"a")/2`
Hence, new surface area `= 6 × ((3"a")/2)^2`
`=(27a^2)/2`
Increase in area` =((27a^2)/2 - 6"a"^2) `
`=(15"a"^2)/2`
% increasein surface area `= ("15a"^2/2xx1/(6"a"^2xx100))%`
=125 %
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