Example 2 - Chapter 7 Class 8 - Proportional Reasoning-1(Ganita Prakash)

Transcript

Example 2 Kesang wanted to make lemonade for a celebration. She made 6 glasses of lemonade in a vessel and added 10 spoons of sugar to the drink. Her father expected more people to join the celebration. So, he asked her to make 18 more glasses of lemonade. To make the lemonade with the same sweetness, how many spoons of sugar should she add? To make 6 glasses of lemonade, Kesang added 10 spoons of sugar So, the ratio of Glasses to Sugar is 6 : 10 Now, we need to make 18 more glasses with the same sweetness So, Ratio of Glasses to Sugar for 18 glasses will be 18 : Number of spoons of sugar in 18 glasses And, both these Ratios will be proportional So, we write 6 : 10 :: 18 : Number of spoons of sugar in 18 glasses Converting into fractions 𝟔/𝟏𝟎=𝟏𝟖/(𝑵𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝒔𝒑𝒐𝒐𝒏𝒔 𝒐𝒇 𝒔𝒖𝒈𝒂𝒓 𝒊𝒏 𝟏𝟖 𝒈𝒍𝒂𝒔𝒔𝒆𝒔) Cross multiplying 6 × Number of spoons of sugar in 18 glasses = 18 × 10 Number of spoons of sugar in 18 glasses = (18 × 10)/6 Number of spoons of sugar in 18 glasses = 3 × 10 Number of spoons of sugar in 18 glasses = 30 Thus, 30 spoons of sugar are needed