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Ex 13.1, 4 - The paint in a certain container is sufficient - Ex 13.1

 

 

  1. Chapter 13 Class 9 Surface Areas and Volumes
  2. Serial order wise
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Ex 13.1, 4 The paint in a certain container is sufficient to paint an area equal to 9.375 m2. How many bricks of dimensions 22.5 cm × 10 cm × 7.5 cm can be painted out of this container? Number of bricks that can be painted out of the container = (𝐴𝑟𝑒𝑎 𝑡ℎ𝑎𝑛 𝑐𝑎𝑛 𝑏𝑒 𝑝𝑎𝑖𝑛𝑡𝑒𝑑 𝑏𝑦 𝑡ℎ𝑒 𝑐𝑜𝑛𝑡𝑎𝑖𝑛𝑒𝑟)/(𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑏𝑟𝑖𝑐𝑘) Area that can be painted by the container = 9.375 m2  = 9.375 × (100)2 cm2 = 9.375 × (10000) cm2 = 93750 cm2 Total surface area of one brick = 2(lb + bh +  lh) = [2(22.5 × 10 + 10 × 7.5 + 22.5 × 7.5)] cm2 = 2(225 + 75 + 168.75) cm2 = (2 × 468.75) cm2 = 937.5 cm2 Number of bricks that can be painted out of the container = (𝐴𝑟𝑒𝑎 𝑡ℎ𝑎𝑛 𝑐𝑎𝑛 𝑏𝑒 𝑝𝑎𝑖𝑛𝑡𝑒𝑑 𝑏𝑦 𝑡ℎ𝑒 𝑐𝑜𝑛𝑡𝑎𝑖𝑛𝑒𝑟)/(𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑏𝑟𝑖𝑐𝑘) = 93750/937.5 = 937500/9375 = 100 ∴ 100 bricks can be painted out by the paint of the container.

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He provides courses for Mathematics from Class 9 to 12. You can ask questions here.
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