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

Transcript

Example 8 For the mid-day meal in a school with 120 students, the cook usually makes 15 kg of rice. On a rainy day, only 80 students came to school. How many kilograms of rice should the cook make so that the food is not wasted?To make meal for 120 students, cook uses 15 kg of rice So, the ratio of Students to Weight of Rice is 120 : 15 Now, we need to make meal for 80 students So, Ratio of Student to Weight of rice will be 80 : Weight of Rice And, both these Ratios will be Proportional So, we write 120 : 15 :: 80 : Weight of Rice Converting into fractions 𝟏𝟐𝟎/𝟏𝟓=𝟖𝟎/(𝑾𝒆𝒊𝒈𝒉𝒕 𝒐𝒇 𝑹𝒊𝒄𝒆) Cross multiplying 120 × Weight of Rice = 80 × 15 Weight of Rice = (𝟖𝟎 × 𝟏𝟓)/𝟏𝟐𝟎 Weight of Rice = (8 × 15)/12 Weight of Rice = (2 × 15)/3 Weight of Rice = 2 × 5 Weight of Rice = 10 Thus, 10 kg of rice is needed so that the food doesn’t get wasted