SIMPLE INTEREST BY: MAYANK AGNIHOTR
IMPORTANT FACTS AND FORMULAE PRINCIPAL: The money borrowed or lent out for a certain period is called the principal or the sum. INTEREST Extra money paid for using others money is called interest. Simple Interest (S.i): If interest on a sum borrowed for a certain period is calculated uniformly, then it is called simple interest. Let Principal = P, Rate-R% per annum (p.a.) and Time = T years. Then 100 PRT ) ; T=(100 PXR RXT Amount (A)-Principal + SI
QUESTIONS Ques 1. A sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 854 in 4 years. Find the Sum. So S.I. for 1 year Rs. (854 - 815) Rs. 39. S.l. for 3 years Rs.(39 x 3) Rs. 117 Principal Rs. (815 - 117) - Rs. 698 Ques 2. How much time will it take for an amount of Rs. 450 to yield Rs.81 as interest at 4.5% per annum of simple interest? Sol. P=450 Rs SI=81 Rs R=4.5 % (100 SI PXR 100x81 450x4.5 - 8100 = (202 )-4 years Ans
Ques 3. Reena took a loan of Rs. 1200 with simple interest for as many years as the rate of interest. If she paid Rs. 432 as interest at the end of the loan period, what was the rate of interest? Sol. Let rate-R% thus time-R years. 1200xRXR 100 SI 100 (2003) 432 1200xR2 R2-432-36 12 R-V36 rate of interest-696 6 ,'. A man took loan from a bank at the rate of 12% pa. simple interest. After 3 years he had to pay Rs. 5400 interest only for the period. Find the principal amount borrowed by him. Ques 4. Sol RXT 100x5400 540000 15000 Rs Ans 12x3 36
Ques 5. A lent Rs. 5000 to B for 2 years and Rs. 3000 to C for 4 years on simple interest at the same rate of interest and received Rs. 2200 in all from both of them as interest. Find the rate of interest per annum. Let rate be R% p.a SI from B Sol. SI from CSI received by A ) + (300100x*) = 2200 5000x2xR 100R + 120R-2200 R-220-1090 p. aAns Ques 6. What will be the ratio of simple interest earned by certain amount at the same rate of interest for 6 years and that for 9 years? Sol. Let the principal be P and rate of interest be R96. (P1006)-6PR Required ratio = 100, = _ ratio(PR9PR 3 --= 2: 3 Ans
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