# Example 9

Last updated at Dec. 8, 2016 by Teachoo

Last updated at Dec. 8, 2016 by Teachoo

Transcript

Example 9 A sum of Rs 1000 is invested at 8% simple interest per year. Calculate the interest at the end of each year. Do these interests form an AP? If so, find the interest at the end of 30 years making use of this fact. We know that Interest = (๐ ร ๐ ร ๐)/100 Here P = Principal , R = Rate , T = Time Given ,P = 1000 , R = 8 % & T = T years Interest at the end of 1st year = (1000 ร 8 ร 1)/100 = Rs 80 Interest at the end of 2rd year = (1000 ร 8 ร 2)/100 = Rs 160 Interest at the end of 3rd year = (1000 ร 8 ร 3)/100 = Rs 240 Therefore, interest at the end of year (1st , 2nd,3rd , โฆ.)forms a series 80, 160 , 240, โฆโฆโฆ. Difference between 2nd and 1st term = 160 โ 80 = 80 Difference between 3rd and 2nd term = 240 โ 160 = 80 Since difference is same Hence it is an AP We have to find interest at the end of 30 years . We know an = a + (n โ 1) d Here , a = 80 , d = 80 , n = 30 Putting these values in formula an = a + (n โ 1)d a30 = 80 + (30 โ 1) 80 = 80 + 29 ร80 = 80 + 2320 = 2400 So, the interest at the end of 30 years = Rs 2400

Chapter 5 Class 10 Arithmetic Progressions

Serial order wise

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CA Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 8 years. He provides courses for Practical Accounts, Taxation and Efiling at teachoo.com .