The radius of a spherical balloon decreased from 21 cm to 14 cm when air is being pumped out of it. Find the ratio of surface areas of the balloons in two cases and percentage decrease in surface area.
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but I didn't got the percentage
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when radius is 21
4pie rsquare
4×pie×21×21
4×pie×441
now when radius is 14
4×pie ×14×14
4×pie ×196
now ratio
4×pie ×441:4×pie ×196
441:196
9:4
4pie rsquare
4×pie×21×21
4×pie×441
now when radius is 14
4×pie ×14×14
4×pie ×196
now ratio
4×pie ×441:4×pie ×196
441:196
9:4
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