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Question 21 (OR 2
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A solid sphere of radius 3 cm is melted and then recast into small spherical balls each of diameter 0.6 cm. Find the number of balls

Last updated at Oct. 1, 2019 by Teachoo

**
Question 21 (OR 2
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**
nd
**
**
question)
**

A solid sphere of radius 3 cm is melted and then recast into small spherical balls each of diameter 0.6 cm. Find the number of balls

Transcript

Question 21 (OR 2nd question) A solid sphere of radius 3 cm is melted and then recast into small spherical balls each of diameter 0.6 cm. Find the number of balls Since the big sphere is melted to make balls Volume of big sphere = Volume of balls Volume of big sphere = Number of balls × Volume of 1 ball ∴ Number of balls = (𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑏𝑖𝑔 𝑠𝑝ℎ𝑒𝑟𝑒)/(𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 1 𝑏𝑎𝑙𝑙) Volume of big sphere Radius = 3 cm Volume of sphere = 4/3 𝜋(𝑟)3 = 4/3×𝜋×(3)^3 = 4/3×𝜋×27 Volume of 1 ball Diameter = 0.6 cm Radius = 0.6/2 = 0.3 cm = 3/10 cm Volume of 1 ball = 4/3 𝜋(𝑟)3 = 4/3×𝜋×(3/10)^3 = 4/3×𝜋×27/1000 Now, Number of balls = (𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑏𝑖𝑔 𝑠𝑝ℎ𝑒𝑟𝑒)/(𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 1 𝑏𝑎𝑙𝑙) = (4/3 × 𝜋 × 27" " )/(4/3 × 𝜋 × 27/1000) = 27" " /( 27/1000) = 27" " /27 × 1000 = 1000 ∴ Number of balls is 1000

CBSE Class 10 Sample Paper for 2019 Boards

Paper Summary

Question 1

Question 2 (Or 1st)

Question 2 (Or 2nd)

Question 3 (Or 1st)

Question 3 (Or 2nd)

Question 4

Question 5

Question 6

Question 7 (Or 1st)

Question 7 (Or 2nd)

Question 8 (Or 1st)

Question 8 (Or 2nd)

Question 9

Question 10

Question 11

Question 12

Question 13

Question 14

Question 15

Question 16 (Or 1st)

Question 16 (Or 2nd)

Question 17 (Or 1st)

Question 17 (Or 2nd)

Question 18

Question 19 (Or 1st)

Question 19 (Or 2nd)

Question 20

Question 21 (Or 1st)

Question 21 (Or 2nd) You are here

Question 22

Question 23 (Or 1st)

Question 23 (Or 2nd)

Question 24

Question 25

Question 26

Question 27 (Or 1st)

Question 27 (Or 2nd)

Question 28 (Or 1st)

Question 28 (Or 2nd)

Question 29

Question 30

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.