Ex 8.3

Chapter 8 Class 7 Comparing Quantities
Serial order wise

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### Transcript

Ex 8.3, 7 (i) Chalk contains calcium, carbon and oxygen in the ratio 10:3:12. Find the percentage of carbon in chalk. Calcium : Carbon : Oxygen = 10 : 3 : 12 Total parts = 10 + 3 + 12 = 25 Percentage of carbon = (ππππ‘π  ππ ππππππ)/(πππ‘ππ ππππ‘π ) Γ 100 = 3/25Γ 100% = 3 Γ 100/25 % = 3 Γ 4% = 12% Ex 8.3, 7 (ii) If in a stick of chalk, carbon is 3g, what is the weight of the chalk stick? Given, Weight of Carbon = 3g Now, We know that Carbon 12% of chalk Weight of Carbon = 12% Γ Weight of chalk 3 = 12% Γ Weight of chalk 3 = 12/100 Γ Weight of chalk 12/100 Γ Weight of chalk = 3 Weight of chalk = 3 Γ 100/12 Weight of chalk = 100/4 Weight of chalk = 25 So, Weight of chalk is 25 g Weight of chalk = 3 Γ 100/12 Weight of chalk = 100/4 Weight of chalk = 25 So, Weight of chalk is 25 g

#### Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.