Question 12 - Figure it out - Page 176, 177 - Chapter 7 Class 8 - Proportional Reasoning-1(Ganita Prakash)

Transcript

Question 12 The ₹10 coin is an alloy of copper and nickel called ‘cupro-nickel’. Copper and nickel are mixed in a 3 : 1 ratio to get this alloy. The mass of the coin is 7.74 grams. If the cost of copper is ₹906 per kg and the cost of nickel is ₹1,341 per kg, what is the cost of these metals in a ₹10 coin?Let’s Find the mass of each metal. Total parts =3+1=4. Mass of 1 part =7.74" " g÷4=1.935" " g. Now, Nickel (1 part): 1.935 g Copper ( 3 parts): 1.935×3=5.805" " g Convert mass to kg (because price is in kg ). Nickel: 1.935÷1000=𝟎.𝟎𝟎𝟏𝟗𝟑𝟓" " 𝐤𝐠 Copper: 5.805÷1000=𝟎.𝟎𝟎𝟓𝟖𝟎𝟓" " 𝐤𝐠 Calculate cost. Cost of Nickel: 0.001935" " kg × ₹1,341≈₹𝟐.𝟓𝟗 Cost of Copper: 0.005805" " kg × ₹906≈₹𝟓.𝟐𝟔 Thus, Total Cost = ₹ 2.59 + ₹ 5.26 = ₹ 7.85 Thus, The cost of the metals in the coin is approximately ₹7.85.