Jawahar Navodaya Vidyalaya Selection Test (JNVST)
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Simple interest
Questions (18)
Question 1: Which is the rate of interest for ₹ 2500 at simple interest to become ₹ 3300 in 4 yr?
Answer: 8%
Explanation:
To find the rate of interest, we use the formula for simple interest: Simple Interest = Principal * Rate * Time / 100. Here, the Simple Interest is the difference between the final amount and the principal: 3300 - 2500 = ₹ 800. We know the Principal is ₹ 2500 and the Time is 4 years. Plugging these into the formula: 800 = 2500 * Rate * 4 / 100. Solving for Rate gives: Rate = (800 * 100) / (2500 * 4) = 8%. Therefore, the rate of interest is 8%.
Question 2: In what time ₹ 4250 amounts to ₹ 5610 at the rate 8 % per annum?
Answer: 4 yr
Explanation:
To find the time, we use the formula for Simple Interest: SI = P * R * T / 100, where P is the principal amount, R is the rate of interest, and T is the time in years. First, we find the Simple Interest (SI) by subtracting the principal from the amount: SI = 5610 - 4250 = 1360. Now, using the formula: 1360 = 4250 * 8 * T / 100. Solving for T, we get T = (1360 * 100) / (4250 * 8) = 4 years.
Question 3: At 25% per annum interest in how many years the simple interest on a sum of money treble itself?
Answer: 8
Explanation:
If the interest rate is 25% per annum, the interest for one year is 25% of the principal. To treble (make three times) the principal, the interest must be 200% of the principal (since the original principal is 100%, and trebling means 300% total). At 25% per year, it will take 200/25 = 8 years for the interest to be 200% of the principal.
Question 4: What is the simple interest on Rs 500 at 2% per annum for 4 yr?
Answer: Rs 40
Explanation:
Simple interest is calculated using the formula: Simple Interest = Principal × Rate × Time / 100. Here, the principal is Rs 500, the rate is 2% per annum, and the time is 4 years. So, Simple Interest = 500 × 2 × 4 / 100 = Rs 40.
Question 5: A person lends ₹ 1500 from a bank. If the bank fixes the rate of interest as 11% per annum, then the amount he has to pay back after 2 yr will be?
Answer: ₹ 1830
Explanation:
To find the total amount to be paid back, calculate the simple interest first. Simple Interest (SI) = Principal x Rate x Time / 100. Here, Principal = ₹ 1500, Rate = 11%, Time = 2 years. SI = 1500 x 11 x 2 / 100 = ₹ 330. The total amount to be paid back is the principal plus the interest, which is 1500 + 330 = ₹ 1830.
Question 6: A sum amounted to ₹ 2486 with the interest of 13% per annum, then what is the sum?
Answer: ₹ 2200
Explanation:
Let the principal amount be P. The interest is 13% of P. So, P + 0.13P = 2486. This simplifies to 1.13P = 2486. Solving for P gives P = 2486 / 1.13 = 2200.
Question 7: A person borrowed a sum of ₹ 20000 for 2 yr on simple interest. He had to repay ₹ 24800 including interest after 2 yr. The rate of interest per annum was
Answer: 12%
Explanation:
The total amount to be repaid is ₹ 24800, and the principal amount is ₹ 20000. The interest for 2 years is ₹ 24800 - ₹ 20000 = ₹ 4800. Using the simple interest formula, Interest = Principal * Rate * Time / 100, we have 4800 = 20000 * Rate * 2 / 100. Solving for Rate, we get Rate = (4800 * 100) / (20000 * 2) = 12%.
Question 8: A person borrowed a sum of ₹ 20000 for 2 yr on simple interest. He had to repay ₹ 24800 including interest after 2 yr. The rate of interest per annum was
Answer: 12%
Explanation:
The total amount to be repaid is ₹ 24800, and the principal amount borrowed was ₹ 20000. The interest paid is ₹ 24800 - ₹ 20000 = ₹ 4800. The formula for simple interest is: Interest = Principal × Rate × Time / 100. Here, Interest = ₹ 4800, Principal = ₹ 20000, and Time = 2 years. Plugging these values into the formula gives: 4800 = 20000 × Rate × 2 / 100. Solving for Rate gives: Rate = (4800 × 100) / (20000 × 2) = 12%.
Question 9: A man borrows ₹ 20000 for the house maintenance which is given by him in 2 yr at 10% per annum. What is the total amount paid by him after 2 yr?
Answer: ₹ 24000
Explanation:
The interest for one year is 10% of ₹ 20000, which is ₹ 2000. For 2 years, the interest is 2 × ₹ 2000 = ₹ 4000. The total amount paid is the principal plus interest: ₹ 20000 + ₹ 4000 = ₹ 24000.
Question 10: What sum will amount to ₹ 6600 in 4 yrs at 8% per annum simple interest?
Answer: ₹ 6000
Explanation:
To find the principal amount (P) that will amount to ₹ 6600 in 4 years at 8% simple interest, we use the formula for simple interest: SI = P * R * T / 100. Here, the amount (A) is ₹ 6600, which is the sum of the principal and the interest: A = P + SI. Rearranging gives us SI = A - P. Substituting the given values, we have: 6600 = P + (P * 8 * 4 / 100). Simplifying, 6600 = P + 0.32P = 1.32P. Solving for P gives P = 6600 / 1.32 = ₹ 5000.
Question 11: What is simple interest on ₹ 1800 for 10 yr at the rate of 10% per annum?
Answer: ₹ 1800
Explanation:
Simple Interest (SI) is calculated using the formula: SI = (Principal × Rate × Time) ÷ 100 - Principal = ₹ 1800 - Rate = 10% - Time = 10 years SI = (1800 × 10 × 10) ÷ 100 = 18000 ÷ 100 = ₹ 1800 Therefore, the simple interest is ₹ 1800.
Question 12: In how many years does the sum of ₹ 1200 become ₹ 1800 at the rate of simple interest of 5% per annum?
Answer: 10
Explanation:
To find the number of years, we use the formula for simple interest: Simple Interest (SI) = Principal (P) × Rate (R) × Time (T) / 100 1. We know the final amount is ₹ 1800, and the principal is ₹ 1200. So, the interest earned is ₹ 1800 - ₹ 1200 = ₹ 600. 2. Use the formula to find the time (T): 600 = 1200 × 5 × T / 100 3. Simplify the equation: 600 = 60T 4. Solve for T: T = 600 / 60 = 10 Therefore, it takes 10 years.
Question 13: In what time ₹3500 will become ₹4130 when annual rate of interest is 6%.
Answer: 3 yr
Explanation:
To find the time, we use the simple interest formula: Interest = Principal × Rate × Time / 100. The interest earned is ₹4130 - ₹3500 = ₹630. Using the formula: 630 = 3500 × 6 × Time / 100. Solving for Time gives us Time = 630 × 100 / (3500 × 6) = 3 years.
Question 14: What is simple interest on ₹ 1800 for 10 yr at the rate of 10% per annum?
Answer: ₹ 1800
Explanation:
Simple interest can be calculated using the formula: Simple Interest = (Principal × Rate × Time) ÷ 100 - Principal (P) = ₹ 1800 - Rate (R) = 10% - Time (T) = 10 years Simple Interest = (1800 × 10 × 10) ÷ 100 = 18000 ÷ 100 = ₹ 1800 Therefore, the correct answer is ₹ 1800.
Question 15: What will be the rate of simple interest at which ₹ 17500 will become ₹ 19250 in 2 yr?
Answer: 5%
Explanation:
To find the rate of simple interest, we first need to calculate the interest earned. The final amount is ₹19250 and the principal amount is ₹17500. The interest earned is ₹19250 - ₹17500 = ₹1750. The formula for simple interest is I = PRT/100, where I is the interest, P is the principal, R is the rate, and T is the time in years. We know I = ₹1750, P = ₹17500, and T = 2 years. Plugging these into the formula gives: 1750 = (17500 * R * 2) / 100 Solving for R, we get: R = (1750 * 100) / (17500 * 2) = 5%. So, the rate of interest is 5%.
Question 16: A man borrows ₹600 from his friend. He agrees to pay it back after 8 months together with simple interest at 8% per annum. What amount will he pay back?
Answer: ₹632
Explanation:
Simple Interest (SI) = Principal (P) * Rate (R) * Time (T) / 100. Here, P = ₹600, R = 8%, T = 8/12 years = 2/3 years. SI = 600 * 8 * (2/3) / 100 = ₹32. Total amount to be paid back = Principal + SI = ₹600 + ₹32 = ₹632.
Question 17: In how many years will ₹ 500 amount to ₹ 600 at the rate of 5% per annum at simple interest?
Answer: 4
Explanation:
Use the formula for simple interest: Simple Interest = Principal × Rate × Time / 100 Here, Principal = 500, Amount = 600, so Interest = 600 - 500 = 100 100 = 500 × 5 × Time / 100 100 = 25 × Time Time = 100 / 25 = 4 years
Question 18: The simple interest on ₹300 at the rate of 6% per annum in 1 1/2 yr will be
Answer: ₹27
Explanation:
Simple Interest (SI) = Principal × Rate × Time / 100 Principal = ₹300, Rate = 6%, Time = 1.5 years SI = 300 × 6 × 1.5 / 100 = ₹27