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Ex 8.3, 7 - Maria invested Rs 8,000 in a business. She would be paid

Ex 8.3, 7 - Chapter 8 Class 8 Comparing Quantities - Part 2
Ex 8.3, 7 - Chapter 8 Class 8 Comparing Quantities - Part 3
Ex 8.3, 7 - Chapter 8 Class 8 Comparing Quantities - Part 4
Ex 8.3, 7 - Chapter 8 Class 8 Comparing Quantities - Part 5
Ex 8.3, 7 - Chapter 8 Class 8 Comparing Quantities - Part 6

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Ex 8.3, 7 Maria invested Rs 8,000 in a business. She would be paid interest at 5% per annum compounded annually. Find (i) The amount credited against her name at the end of the second year. Given, Principal (P) = Rs 8000 Rate (R) = 5% per annum Time = 2 Years We need to find the amount after 2 years So, we use the formula A = P ("1 + " 𝑟/100)^𝑛 Putting values A = 8000 ("1 + " 5/100)^2 = 8000 ("1 + " 1/20)^2 = 8000 ((20 + 1)/20)^2 = 8000 (21/20)^2 = 8000 × ((21 × 21)/(20 × 20)) = 80 × ((21 × 21)/(2 × 2)) = 20 × 21 × 21 = 20 × 441 = 8820 ∴ Amount after 2 years = Rs 8,820 Ex 8.3, 7 (Method 1) Maria invested Rs 8,000 in a business. She would be paid interest at 5% per annum compounded annually. Find (ii) The interest for the 3rd year. Interest in 3rd year = Amount after 2 years × Rate = 8820 × 5/100 % = 8820 × 5/100 = 8820 × 1/20 = 882/2 = 441 ∴ Interest for the 3rd year = Rs 441 Ex 8.3, 7 (Method 2) Maria invested Rs 8,000 in a business. She would be paid interest at 5% per annum compounded annually. Find (ii) The interest for the 3rd year. Now, Interest for the 3rd year = Amount after 3 years − Amount after 2 years Finding Amount after 3 years Amount after 3 years = P (1+𝑅/100)^𝑛 Putting values Amount = 8000 (1+5/100)^3 = 8000 (1+1/20)^3 = 8000 ((20 + 1)/20)^3 = 8000 (21/20)^3 = 8000 × (21 × 21 ×21)/(20 × 20 ×20) = 8000 × (441 × 21)/(400 × 20) = 8000 × 9261/8000 = 9261 Therefore, Interest for the 3rd year = Amount after 3 years − Amount after 2 years = 9261 − 8820 = 441 ∴ Interest for the 3rd year = Rs 441

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.