# Ex 13.2, 10 - Chapter 13 Class 8 Direct and Inverse Proportions

Last updated at Nov. 12, 2018 by Teachoo

Last updated at Nov. 12, 2018 by Teachoo

Transcript

Ex 13.2, 10 Two persons could fit new windows in a house in 3 days. (i) One of the persons fell ill before the work started. How long would the job take now? Given, 2 person can fit the window in 3 days. If one person fell ill, then, only one person will do the job. We need to find how long will it take to do the job Let the time taken 𝑦 days Thus, our table looks like As we increase the number of persons, the time taken to complete the job decreases ∴ They are in inverse proportion 2 × 3 = 1 × 𝑦 6 = 𝑦 𝑦 = 6 ∴ 1 person will complete the job in 6 days. Ex 13.2, 10 Two persons could fit new windows in a house in 3 days. (ii) How many persons would be needed to fit the windows in one day? We need to find how many persons would fit the window in 1 day Let number of persons be x Thus, our table looks like Since number of persons and time taken are in inverse proportion 2 × 3 = 𝑥 × 1 6 = 𝑥 𝑥 = 6 ∴ 6 persons will fit the windows in 1 day.

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Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.