SSC CGL (Prelims) Maths: Simple Interest questions with solutions

Q1. If ₹1,875 becomes ₹2,625 in 4 years, what will ₹24,000 become at the end of 9 years at the same rate of interest, under simple interest?

1. ₹45,600
2. ₹21,600
3. ₹34,800
4. ₹43,200

Answer: ₹45,600

The increase from ₹1,875 to ₹2,625 is ₹750 in 4 years, so yearly interest is ₹187.5. On ₹1,875, the rate is 10% per annum, since ₹187.5 is 10% of ₹1,875. For ₹24,000 at 10% for 9 years, SI = ₹21,600, so amount = ₹45,600.

Q2. Sohan borrows a sum of ₹1,41,545 at the rate of 11% per annum simple interest. At the end of the first year, he repays ₹25,490 towards the principal amount borrowed. If Sohan clears all pending dues at the end of the second year, including the interest accrued during the first year, how much does he pay at the end of the second year?

1. 1,44,391
2. 1,36,453
3. 1,41,222
4. 1,37,407

Answer: 1,44,391

First-year interest on ₹1,41,545 at 11% is ₹15,570. After paying ₹25,490, the outstanding principal becomes ₹1,16,055. Interest for the second year on this amount is ₹12,766.05, so the final payment is the remaining principal plus second-year interest, matching the given option.

Q3. Simple interest on a certain sum is one-fifth of the sum, and the rate of interest per cent per annum is 5 times the number of years. If the rate of interest increases by 3%, then what will be the simple interest (in ₹) on ₹5,600 for 6 years?

1. ₹4668
2. ₹4168
3. ₹4268
4. ₹4368

Answer: ₹4368

Use the relation SI = PRT/100 and the condition that SI is one-fifth of the sum. Also, the rate is 5 times the number of years, so the original rate can be determined from the given relation. After increasing the rate by 3%, compute SI on ₹5,600 for 6 years.

Q4. Kiran lent ₹4,000 to two persons, one part at the rate of 8% per annum and the remaining part at the rate of 10% per annum. He got an annual simple interest of ₹352. Then the sum lent at 10% is:

1. ₹1,800
2. ₹2,200
3. ₹2,400
4. ₹1,600

Answer: ₹1,600

If \(x\) is lent at 10%, then \(4000-x\) is lent at 8%. The total simple interest for one year is \(0.10x+0.08(4000-x)=352\), which gives \(x=1600\).

Q5. If the simple interest on ₹10,000 for 4 years is ₹4,000, what is the rate of interest per annum?

1. 8%
2. 10%
3. 12%
4. 5%

Answer: 10%

Using the formula $SI = \frac{PRT}{100}$, we get $4000 = \frac{10000 \times R \times 4}{100}$. Solving gives $R = 10\%$.

Q6. If a sum of money doubles in 8 years at simple interest, how long will it take to triple?

1. 16 years
2. 12 years
3. 24 years
4. 20 years

Answer: 16 years

If the money doubles in 8 years, the simple interest earned in 8 years equals the principal. To triple the money, the interest must become twice the principal, which will take twice as long. Hence, the required time is 16 years.

Q7. Find the simple interest on ₹5000 at 6% per annum for 2 years.

1. ₹600
2. ₹500
3. ₹550
4. ₹620

Answer: ₹600

Simple interest is calculated using SI = (P × R × T) / 100. Substituting P = 5000, R = 6, and T = 2 gives SI = 600. Hence, the simple interest is ₹600.