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The radius of a spherical balloon increases from 7 cm to 14 cm as air is being pumped into it. Find the ratio of surface areas of the balloon in the two cases. - Mathematics

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प्रश्न

The radius of a spherical balloon increases from 7 cm to 14 cm as air is being pumped into it. Find the ratio of surface areas of the balloon in the two cases.

बेरीज
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उत्तर

Radius (r1) of spherical balloon = 7 cm

Radius (r2) of the spherical balloon, when air is pumped into it = 14 cm

Required ratio = `"Initial surface area"/"Surface area after pumping air into a balloon"`

= `(4pir_1^2)/(4pir_2^2)` = `(r_1/r_2)^2`

= `(7/14)^2` = `1/4`

Therefore, the ratio between the surface areas in these two cases is 1 : 4.

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पाठ 11: Surface Area and Volumes - EXERCISE 11.2 [पृष्ठ १४५]

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एनसीईआरटी Mathematics [English] Class 9
पाठ 11 Surface Area and Volumes
EXERCISE 11.2 | Q 4. | पृष्ठ १४५

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