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A Solid Metallic Sphere of Radius 5.6 Cm is Melted and Solid Cones Each of Radius 2.8 Cm and Height 3.2 Cm Are Made. Find the Number of Such Cones Formed. - Mathematics

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प्रश्न

A solid metallic sphere of radius 5.6 cm is melted and solid cones each of radius 2.8 cm and height 3.2 cm are made. Find the number of such cones formed. 

थोडक्यात उत्तर

उत्तर

Let the number of such cones formed be n
Now, Volume of solid metallic sphere = Volume of n solid cones

\[\Rightarrow \frac{4}{3} \times \frac{22}{7} \times \left( 5 . 6 \right)^3 = n \times \frac{1}{3} \times \frac{22}{7} \times \left( 2 . 8 \right)^2 \times 3 . 2\]

\[ \Rightarrow 4 \times \left( 5 . 6 \right)^3 = n \times \left( 2 . 8 \right)^2 \times 3 . 2\]

\[ \Rightarrow n = 28\]

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पाठ 14: Surface Areas and Volumes - Exercise 14.1 [पृष्ठ २९]

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आरडी शर्मा Mathematics [English] Class 10
पाठ 14 Surface Areas and Volumes
Exercise 14.1 | Q 22 | पृष्ठ २९

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Assertion (A)
If the volumes of two spheres are in the ratio 27 : 8, then their surface areas are in the ratio 3 : 2.

Reason (R)
Volume of a sphere `=4/3pi"R"^3`
Surface area of a sphere = 4πR2


  1. Both Assertion (A) and Reason (R) are true and Reason (R) is a correct explanation of Assertion (A).
  2. Both Assertion (A) and Reason (R) are true but Reason (R) is not a correct explanation of Assertion (A).
  3. Assertion (A) is true and Reason (R) is false.
  4. Assertion (A) is false and Reason (R) is true.

Find the surface area of a sphere of radius 7 cm.

Solution :

The surface area of the sphere = 4πr2

= `4 xx 22/7 xx square^2`

= `4 xx 22/7 xx square`

= `square xx 7`

∴ The surface area of the sphere = `square` sq.cm.


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