Simple Interest Questions with Solutions | Set 1 (Q1 to Q10)

This set contains Simple Interest Questions with Solutions — Set 1 (Q1 to Q10) covering a mix of question types and difficulty levels — from basic to advanced — exactly as asked in real competitive exams.

Solutions are written in a simple, step-by-step notebook style for easy self-study and quick understanding. Each solution is broken down step by step so even the toughest question feels easy. These questions are hand-picked for students preparing for SSC CGL, SSC CHSL, CAT, Bank PO, Bank Clerk, UPSC CSAT, Railway RRB, AMCAT, eLitmus, TCS NQT and all campus placement aptitude tests. International students preparing for GRE, GMAT, SAT, ACT, MAT and all Numerical Reasoning Tests will find these equally useful.

✏️ Attempt each question on your own first — then check the solution below.

1. What annual payment will discharge a debt of Rs. 1620 dues in 5 years at 4% p.a. SI.

2. A sum of Rs. 5000 is lent for 4 years at the rate of 5% p.a. at SI. Find the interest.

3. If the simple interest on Rs. 900 increases by Rs. 30 when the time increases by 2 years. Find the rate percent per annum.

4. A man deposited Rs. 5460 in a bank  at 3% p.a. and Rs. 5980 in another bank at 7% p.a. Find the rate of interest for the whole sum.

5. The simple interest on a sum of money is \(\frac{9}{{16}}\) of principal, and the number of years is equal to the rate percent per annum. Find rate percent.

6. A sum was put on SI at a certain rate for 3 years. Had it been put at 5% higher rate it would have fetched Rs. 750 more, find the sum.

7. The SI on a sum of money will be Rs. 200 in after 5 year. For the next 7 years principal becomes 6 times, what will be the total interest at the end of 12 years.

8. A certain sum is invested for a certain time period. It amounts to Rs. 200 at 5% p.a. But when invested at 10% p.a., it amounts to Rs. 300. Find the time.

9. If the simple interest on Rs. 1660 be more than SI of 1560 Rs. by Rs. 30 in 5 years. Find the rate percent per annum.

10. If the simple interest on Rs. 440 increases by Rs. 55, when the rate percent increases by 5% p.a. Find the time.

1. What annual payment will discharge a debt of Rs. 1620 dues in 5 years at 4% p.a. SI.
Sol:
B = 1620
n = 5
y = 1
r = 4%
∴ B = \(na + \frac{{ra}}{{100y}} \times \frac{{n(n – 1)}}{2}\)

1620 = \(5a + \frac{{4a}}{{100 \times 1}} \times \frac{{5 \times 4}}{2}\)

a = 300 Rs.      Answer

Method(2):

∴ installment = 100 unit = 100×3 = 300 Rs.          Answer

2. A sum of Rs. 5000 is lent for 4 years at the rate of 5% p.a. at SI. Find the interest.
Sol:
SI = \(\frac{{5000 \times 4 \times 5}}{{100}}\) = 1000 Rs.      Answer

3. If the simple interest on Rs. 900 increases by Rs. 30 when the time increases by 2 years. Find the rate percent per annum.
Sol:
Method(1):

\(\frac{{900 \times r \times (t + 2)}}{{100}} – \frac{{900 \times r \times t}}{{100}} = 30\)

\(\frac{{900 \times r \times 2}}{{100}} = 30\)
r = \(\frac{5}{3}\)%     Answer

Method(2):

\(\frac{{900}}{{100\% }}\left( {r(t + 2) – rt} \right)\% = 30\)

\(\frac{{900 \times 2r}}{{100}} = 30\)

r = \(\frac{5}{3}\)%     Answer

4. A man deposited Rs. 5460 in a bank  at 3% p.a. and Rs. 5980 in another bank at 7% p.a. Find the rate of interest for the whole sum.
Sol:

∴ x = \(\frac{{3 \times 21 + 7 \times 23}}{{21 + 23}}\)
= 5.09%    Answer

5. The simple interest on a sum of money is \(\frac{9}{{16}}\) of principal, and the number of years is equal to the rate percent per annum. Find rate percent.
Sol:

\(\frac{9}{{16}}P\) = \(\frac{{P \times r \times r}}{{100}}\)
r² = \(\frac{{900}}{{16}}\)
r = \(\frac{{30}}{4}\) = 7.5%     Answer

6. A sum was put on SI at a certain rate for 3 years. Had it been put at 5% higher rate it would have fetched Rs. 750 more, find the sum.
Sol:
SI ∝ rt
∴ if r ↑ 5% higher then it would fetch extra 3×5% = 15% interest.
⟹

7. The SI on a sum of money will be Rs. 200 in after 5 year. For the next 7 years principal becomes 6 times, what will be the total interest at the end of 12 years.
Sol:

required SI = \(200 + \frac{{200}}{5} \times 7 \times 6\)
= 1880 Rs.    Answer

8. A certain sum is invested for a certain time period. It amounts to Rs. 200 at 5% p.a. But when invested at 10% p.a., it amounts to Rs. 300. Find the time.
Sol:
Make principal same in both the cases
\(\frac{{200}}{{(100 + 5t)\% }} \times 100\% = \frac{{300}}{{(100 + 10t)\% }} \times 100\% \)
300 + 15t = 200 + 20t
5t = 100
t = 20 years       Answer

9. If the simple interest on Rs. 1660 be more than SI of 1560 Rs. by Rs. 30 in 5 years. Find the rate percent per annum.
Sol:

\(\frac{{1660}}{{100\% }} \times 5r\% – \frac{{1560}}{{100\% }} \times 5r\% = 30\)

\(\frac{{100}}{{100}} \times 5r = 30\)

r = 6%     Answer

10. If the simple interest on Rs. 440 increases by Rs. 55, when the rate percent increases by 5% p.a. Find the time.
Sol:

\(\frac{{100\% }}{{440}} \times 55 = (r + 5)t\% – rt\% \)
\(\frac{{25}}{2}\) = 5t%
t = 2.5 years       Answer

✅ Well done on completing Set 1!

Continue practising with Simple Interest Questions 11 to 20 → Set 2 or revisit the Simple Interest Concept Page to strengthen your formulas and tricks before moving ahead.

Consistent practice is the key to mastering simple interest for SSC CGL, SSC CHSL, CAT, Bank PO, Bank Clerk, UPSC CSAT, Railway RRB, AMCAT, eLitmus, TCS NQT and international exams including GRE, GMAT, SAT, ACT, MAT and all Numerical Reasoning Tests. Want to understand the concept better? Read about Interest on Wikipedia before attempting the next set.

This page is part of our complete series of simple interest questions with solutions for competitive exams — covering every question type from basic to advanced so you can build speed, accuracy and confidence. Practising these questions regularly will also strengthen your core simple interest concept before your exam day.