Class 8: Chapter 15 Simple Interest and Compound Interest Exercise 15A

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1 Class 8: Chapter 1 Simple Interest and Compound Interest Exercise 1A Q1. Find the simple interest and amount on: i. Rs. 00 for 1 years at 7 % per annum 3 S. I. P Rs. 000, R 7 3 % 3 3 % T 1 year year S. I Rs. 86 Amount P + S. I Rs. 36 ii. iii. Rs for 6 years 3 months at 8% per annum P Rs R 8% T 6 1 year / year () S. I. ( ) Rs Amount Rs Rs. 90 Rs for 11 months at 9 3 % per annum P Rs. 1900, R 9 3 % 39 % T 11 Months 11 1 years S. I. Rs Rs Amount P + SI Rs. ( ) Rs

2 iv. Rs. 800 for 7 days at 6 1 % per annum P Rs. 800, R 66 1 % 13 % T 7 days 7 36 years S. I. Rs Amount Rs Rs. 780 Q. Find the simple interest on Rs.8600 from 18 th October, 006 to 13 th march, 007 at 8% per annum. Also find the amount. P Rs R 8% T 18 Oct. to 13 March ( ) days 16 days years S. I Rs. 36 Rs. 7.0 Amount P + S. I. Rs Rs Q3. Ashish lent Rs.1000 to Mark at 7% per annum simple interest. After years, Mark discharged the debt by giving a watch and Rs.3000 in cash. What is the value of the watch? P Rs. 1000, R 7%, T years S. I Rs. 367 Amount P + S. I. Rs Rs. 117 The value of watch Amount Rs Rs Rs. 117 Q. In what time will the simple interest on Rs.760 be Rs.110 at 6 1 % per annum? P Rs. 760, S. I. 110., R 6 1 % % We are requires to compute time in years.

3 S. I. S. I. T P R years years months Q. In how much time will Rs.600 amount to Rs.366, when money is worth 9 1 %per annum simple interest? Amount Rs. 366, P Rs. 600 S. I. Amount P Rs. ( ) Rs. 6 R 9 1 % 37 % S. I. S. I. T P R years or years 3 months Q6. At what rate per cent per annum will Rs.16 amount to Rs.080 in 3 1 years? P Rs. 16, Amount Rs. 080, T 3 1 years 7 years We have to compute rate of interest R S. I. S. I. R P T. (1) S. I. Amount P Rs. (080 16) Rs. Substituting the value of S. I. P & T in Equal (1) we get R % 3

4 Q7. At what rate per cent per annum will the simple interest on Rs.670 be Rs.1911 in 3 years 3 months? P Rs. 670, S. I. Rs Time 3 year 3 months 3 1 years 13 year We have to compute R. S. I. S. I. R P T % 8 3 % Q8. At what rate per cent of simple interest will a sum of money double itself in 1 years? Principle P x Amount x S. I. x Time 1 years We have to compute R S. I.. S. I. R P T x x 1 8 years months 1 Q9. Simple interest will a sum is 9 are numerically equal. Let Principle P Rs. x 9 S. I. Rs. 16 x Numerical R T S. I.. We have to compute R. S. I. R P T T R R S. I. P 9 x 16 9 x 16 R % 16 of the sum. Find the rate per cent and the time if both

5 Per annum, T 7 1 years Q10. What sum will yield Rs.06 as simple interest in 1 year months at 6 1 % per annum? S. I. Rs. 06 T 1year months years R 6 1 % % We are required to compute P S. I. S. I. P R T Rs. 68 Q11. What sum will amount to 178 in 1 years at 7 1 % per annum simple interest? Amount Rs. 178, T. 1 years, S 7 1 % We have to compute P P R T S. I.. S. I. P R T S. I. Amount P (178 P) (178 P) P P 1 (178 P) P ( + 7 ) 178 P ( 7 ) P 7 Rs. 17

6 Q1. A sum of money becomes 8 of itself in years at certain rate of simple interest. Find the rate of interest. Let P Rs. x, Amount Rs. 8 x Time T years We have to compute rate of interest R. S. I. Rs. ( 8 x x) Rs. 3 x S. I. S. I. R P T 3 x x 300 1% p. a. Q13. What sum of money lent at 1 1 % per annum will produce the same interest in years as Rs.860 produces in years at 1% per annum? Consider P Rs. 860, R 1%, T years S. I Rs. 136 Now we have to compute P if T years, R 1 1 % and S. I. Rs. 316 S. I. S. I. P R T Rs. 107 Q1. If Rs.10 amount to 10 in 3 years at simple interest, what will Rs.3 amount to in years at the same rate? First compute R for P Rs. 10, Amount Rs. 10, T 3 Years S. I. Amount P

7 Rs. 300 Now for S. I. Rs. 300 S. I. R P T 300 8% p. a Now for R 8%, P Rs. 300, T years S. I Rs. 10 Amount P + S. I Rs. Q1. A sum of money lent at simple interest amounts to Rs.3 in years and Rs.160 in years. Find the sum and the rate of interest Given is; (1) Amount Rs. 3, T years () Amount Rs. 160, T years P and R are the same in both the above area from the data given in (i) S. I. Rs. (3 P) P R 3 P.. (i) From data given in (ii) S. I. Rs. 160 P P R 160 P. ii) Divide equation (i) by equation (ii) P R 3 P 160 P P R (3 P) (160 P) 3 P 160 P 3P P 3 Rs. 600 From data set (i) S. I. Rs. (3 600) Rs. 6 S. I. 7

8 R S. I. P T % p. a. Q16. A lead Rs.00 to B and certain sum to C at the same time at 7% per annum simple interest. If after years, a altogether receives Rs.110 as interest from B and C find the sum lent to C. For A, P Rs. 00, R 7% p. a. and, T years S. I. due from A 00 7 Rs. 700 Total interest received from both B & C Rs. 110 Total interest received from C Rs Rs. 0 Now we have to compute sum rent to P S. I. P R T S. I. Rs. 0, T years, R 7% p. a. 0 Therefore, P Rs The amount rent by A to C Rs. 100 Q17. The simple interest on a certain sum for 3 years at 8% per annum is Rs.96 more than the simple interest on the same sum for years at 9% per annum. Find the sum. S. I. (i) for a sum P, for; T 3years, R 8% p. a. S. I. (1) P 8 3 (i) S. I. ()for a sum P, for, T years, R 9% p. a. S. I. () P 9 ii) S. I. (1) S. I. () + 96 P P P ( 18 ) 96 P P Rs The sum Rs Q18. Two equal sums of money were lent at simple interest at 11% p.a. for 3 1 years and 1 years respectively. If the difference for two periods was Rs.1.0, find each sum. 8

9 S. I. (1) for sum P, R, 11%, T 3 1 year S. I. ( )in the S. I. for sum P, R 11%, T 1 years S. I. (1) P S. I. () P 11 1 Given S. I. () S. I. (1) Rs. 1. P 11 1 P P P 11 Rs. 370 The equal sums are Rs. 370 each 9 1. Q19. Divide Rs.6000 into two parts so that the simple interest on the first pat for 9 months at 1% per annum is equal to the simple interest on the second part for 1 ½ years at 10% per annum. Let Rs. x be one part of the sum, Rs. (6000 x) be other part of sum. S. I. (1)is the S. I. on P Rs. x, for T 9months 3 S. I. (1) x 1 3 i) S. I. () is S. I. on Rs. ( 6000 x) for R 10%, T 1 1 years S. I. () x 1 3 (6000 x) S. I. 1 S. I. (6000 x) x 9 (6000 x) 1 9x + 1x x years, at R 1%

10 x Rs. 370 The Two Parts are; Rs. 370 and Rs. 0 Q0. Divide a sum of Rs.1300 into two parts such that if one part be lent at % per annum for years 9 months and the other at 7 1 % per annum for 1 years 8 months, the total interest received is Rs.37. Let Rs. x be the first part of the sum. Then Rs. (1300 x) becomes the second part of the sum. S. I. (1)is the interest of P x, R %, T years 9 months 3 years S. I. (1) x x 100 x S. I. () is the interest on P 1300 x, 100 R 7 1 % p. a. T (1300 x) 7 1 S. I. 1 3 Given, S. I. (1) + S. I. () 37 7x 7 + (1300 x) year 8 months years (1300 x) x + 10(1300 x) x 10x x x 6600 The one part of sum is Rs and second part Rs Q1. In what time will a sum of money lent at8 1 1 % simple interest become times of 3 itself. Let P be the sum lent. Amount P, R % We have to compute T. S. I. P P 3P 10

11 3P P T T T years Q. A certain sum of money lent out at 6 /3% p.a. produced the same simple interest in 6 years as Rs.300 lent out at 8 % p.a. for 7 years. Find the sum Let P be the sum lent. R 6 3 %, T 6 years S. I. (1) be the simple interest earned S. I. (1) P Le S. I. () be the 0 P 10 P S. I. for P 300, R 8 %, T 7% p. a. S. I. () Given, S. I. (1) S. I. () P P 70 The sum lent is Rs. 70 Q3. Naveen and Praveen borrowed Rs.000 and Rs.000 respectively for 3 1 years at the same rate of interest. If Praveen has to pay Rs.360 more than Naveen, find the rate of interest. Let R be the rate interest S. I. (1) be the S. I. paid by Naveen, for P Rs. 000, T years 7 years, S. I. (1) 000 R R S. I. ()be the S. I. paid by Praveen for P Rs. 000, T 31/ years 7/ years, 11

12 Given S. I. () S. I. (1) 360 i. e. 7 7R 10 7R 360 (7 10) 7R R 360 R 360 8% p. a. 6 7 Q. A sum of money was put at simple interest at a certain rate for years. If this sum had been put at 3% higher rate, it would have earned Rs.70 more as interest. Find the sum. Let P be the sum lent S. I. (1) is interest for sum P, Rate interest R and T years, P R P R S. I. (1) 0 Let S. I. () is the interest for sum P for interest rate (R + 3) P (R + 3) S. I. () Given, S. I. () S. I. (1) Rs. 70 P (R + 3) P R 70 P R + P 3 6P P Sum lent is Rs P R 70 Q. A sum of money invested at 6% p.a. simple interest for a certain period of time yield Rs.960 as interest. If this sum had been invested for years more, it would have yielded Rs.160 as interest. Find the sum. Let sum lent is Rs. P, R 6%, T years P 6 T S. I. (1) Given, S. I. (1) Rs. 960 P 6 T 960 1

13 P T For sum Rs. P, R 6%, T years, S. I. () is the S. I. P 6 (T + ) S. I. () 160 P 6 T + P From eq. (1), P T P P P The sum Rs

Compound Interest Questions Quiz for CDS, CLAT, SSC and Bank Clerk Pre Exams.

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