Vanishree Singh
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(i) Chalk contains Calcium, Carbon and Oxygen in the ratio 10:3:12. Find the percentage of Carbon in chalk. (ii) If in a stick of chalk, Carbon is 3 g, what is the weight of the chalk stick?

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NCERT Solutions for Class 7 Mathematics Chapter 8
Important NCERT Questions
Class vii Math Chapter 8 Comparing Quantities Exercise 8.3
NCERT Books for Session 2022-2023
CBSE Board
Questions No: 7

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1 Answer

  1. (i) Given ratio = 10 : 3 : 12
    Total part = 10 + 3 + 12 = 25
    Part of Carbon = 3/25
    Percentage of Carbon part in chalk = 3/25×100 = 12%

    (ii) Quantity of Carbon in chalk stick = 3 g
    Let the weight of chalk be x g.
    Then, 12% of x = 3
    ⇒ 12/100 X x=3
    ⇒ x = 3×100/12 = 25 g
    Hence, the weight of chalk stick is 25 g.

    lass 7 Maths Chapter 8 Exercise 8.3

    for more answers vist to:
    https://www.tiwariacademy.com/ncert-solutions/class-7/maths/chapter-8/

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