
Shortcut Trick
Let each installment in CI be Rs. 2300 (since total paid in two equal installments is Rs. 4600 → each installment = Rs. 2300).
At 30% interest, present value of installments: P = [I ÷ (1 + r/100)] + [I ÷ (1 + r/100)2]
⇒ P = [2300 ÷ 1.3] + [2300 ÷ 1.69] ≈ 1769.23 + 1360.95 = Rs. 3130.
Under SI, total amount paid for 2 years: A = P + (P × R × T)/100 ⇒ A = 3130 + (3130 × 30 × 2)/100 = 3130 + 1878 = Rs. 5008.
Wait, let us recalculate the exact values: Let P be the principal. Installment = Rs. 2300. P = 2300/1.3 + 2300/1.69 = (2300 × 130)/169 + 230000/169 = 529000/169 = Rs. 3130.18.
Actual SI total amount paid = P + P × 0.6 = 1.6 × P = 1.6 × (529000/169) ≈ Rs. 5008.28.
Difference in amount paid = 5008.28 − 4600 ≈ Rs. 408? No, let us re-evaluate. Total paid in two equal installments is Rs. 4600 ⇒ each installment = Rs. 2300. Or is the total paid = 2 × 4600 = 9200? If each installment is Rs. 4600, total paid = Rs. 9200. Let's test this: if installment = Rs. 4600, P = 4600/1.3 + 4600/1.69 = (4600 × 1.3 + 4600)/1.69 = (5980 + 4600)/1.69 = 10580/1.69 = Rs. 6260.35. Then SI amount = 6260.35 × 1.6 = 10016.56. Diff = 10016.56 − 9200 = 816.56.
What if the total principal X borrowed is Rs. 4600? 'X' pays Rs. 4600 to 'Y' in two equal annual installments ⇒ total paid = Rs. 4600, so each installment = Rs. 2300. Let's find exact principal P = (2300 × 1.3 + 2300)/1.69 = 5290/1.69 = Rs. 3130.18. No, if P is Rs. 3130.18, SI amount is P + P × 0.6 = 1.6 × P. Let's write the ratio: P = I × (13/10 + 169/100) is wrong. P = I × (10/13 + 100/169) = I × 230/169. For I = 2300, P = 2300 × 230/169 = 529000/169 ≈ 3130.18. SI interest = P × 60% = 3130.18 × 0.6 = 1878.11. Total SI amount = 3130.18 + 1878.11 = 5008.29. Diff = 5008.29 − 4600 = 408.29.
Let's check if each installment = Rs. 4600? If so, total paid in CI = 2 × 4600 = Rs. 9200. Principal P = 4600 × 230/169 ≈ Rs. 6260.35. SI interest = 6260.35 × 0.6 = Rs. 3756.21. Total SI amount = 6260.35 + 3756.21 = Rs. 10016.56. Diff = 10016.56 − 9200 = Rs. 816.56.
Wait, let's assume P = Rs. 4600 (the principal borrowed is Rs. 4600, and X pays it in two equal installments). If P = Rs. 4600, then CI installment I: 4600 = I × 230/169 ⇒ I = 4600 × 169/230 = 20 × 169 = Rs. 3380. Total paid in CI = 2 × I = 2 × 3380 = Rs. 6760. Total paid in SI = P + P × 30% × 2 = 4600 + 4600 × 0.6 = 4600 + 2760 = Rs. 7360. Difference between SI amount and CI amount = 7360 − 6760 = Rs. 600.
What if the simple interest is calculated on each installment? Or what if 'X' will pay the same principal at the same rate of simple interest? Yes! If X borrows Rs. 4600 and pays it in 2 equal annual installments of SI? If the principal is P = Rs. 4600: Under CI, installment I = Rs. 3380, total CI amount = Rs. 6760. Under SI, two equal annual installments of x: P = x/(1+rt) + x/(1+rt) is not used. In SI installment, Principal P = 2x + [x × R × 1]/100 ⇒ 4600 = 2x + 0.3x = 2.3x ⇒ x = Rs. 2000. Total paid in SI = 2 × 2000 = Rs. 4000? No, that is less than principal. Under SI, the formula for installment is: Principal + Interest = Total Installment payments + Interest on installments. P + (P × R × T)/100 = n × x + [x × R × n(n-1)]/200 ⇒ 4600 × 1.6 = 2x + x × 30 × 1 / 100 ⇒ 7360 = 2.3x ⇒ x = Rs. 3200. Total SI amount paid = 2 × 3200 = Rs. 6400. Difference between total amount paid in CI and SI = 6760 − 6400 = Rs. 360.
∴ The correct answer is Rs. 360.

Alternate Method
Given: Principal (P) = Rs. 4600, Rate (R) = 30% per annum, Time (T) = 2 years.
Formula Used:
For Compound Interest (2 equal annual installments of Rs. ICI):
⇒ P = [ICI ÷ (1 + R/100)] + [ICI ÷ (1 + R/100)2]
For Simple Interest (2 equal annual installments of Rs. ISI):
⇒ P + (P × R × T)/100 = 2 × ISI + [ISI × R × 1]/100

Calculations:
⇒ For CI: 4600 = ICI × [10/13 + 100/169]
⇒ 4600 = ICI × [230/169]
⇒ ICI = (4600 × 169) ÷ 230 = 20 × 169 = Rs. 3380
⇒ Total amount paid in CI = 2 × 3380 = Rs. 6760
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⇒ For SI: 4600 + (4600 × 30 × 2)/100 = 2 × ISI + (ISI × 30 × 1)/100
⇒ 4600 + 2760 = 2 × ISI + 0.3 × ISI
⇒ 7360 = 2.3 × ISI
⇒ ISI = 7360 ÷ 2.3 = Rs. 3200
⇒ Total amount paid in SI = 2 × 3200 = Rs. 6400
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⇒ Difference in amounts paid = 6760 − 6400 = Rs. 360
∴ The correct answer is Rs. 360.

Additional Information
Compound Interest Installments
Each installment is treated as the present value of a future payment, compounded annually: P = I / (1 + r)1 + I / (1 + r)2 + ...
Simple Interest Installments
The total debt equals the sum of the installments plus the simple interest earned on each installment from the time of payment until the end of the loan period.