
Shortcut Trick
Balance Principal = 65000 − 41000 = ₹24,000
Due amount after 5 months = 24000 + (24000 × 25 × 5) ÷ 1200 = ₹26,500
Sum of 5 instalments (₹x) = 5x + [x × 25 × (4 + 3 + 2 + 1)] ÷ 1200 = 125x/24
Equating both values: 125x/24 = 26500 ⇒ x = 5088
∴ The correct answer is ₹5,088.

Alternate Method
Given:
Cash price of the scooter = ₹65,000
Down payment = ₹41,000
Rate of simple interest (R) = 25% p.a.
Number of monthly instalments (n) = 5
Instalment Calculation Timeline Month 0 ₹24000 Month 1 ₹x Month 2 ₹x Month 3 ₹x Month 4 ₹x Month 5 ₹x Due = ₹26,500 x = ₹5,088
Formula Used:
Total Due Amount = Principal + Simple Interest
Simple Interest = (P × R × T) ÷ 100
Sum of Instalments = x × n + Interest on instalments for the remaining months
Calculations:
⇒ Balance Principal (P) = ₹65,000 − ₹41,000 = ₹24,000
⇒ Time for the Due Amount = 5 months = 5/12 years
⇒ Due Amount after 5 months = 24000 + (24000 × 25 × 5) ÷ (100 × 12)
⇒ Due Amount = 24000 + 2500 = ₹26,500
⇒ Let each monthly instalment be ₹x.
⇒ Sum of 5 instalments along with interest accrued till the 5th month:
⇒ First instalment earns interest for 4 months, second for 3 months, and so on.
⇒ Total Amount = 5x + [x × 25 × (4 + 3 + 2 + 1 + 0)] ÷ (100 × 12)
⇒ Total Amount = 5x + [x × 25 × 10] ÷ 1200
⇒ Total Amount = 5x + 250x ÷ 1200 = 5x + 5x/24 = 125x/24
⇒ Equating Both Values: 125x/24 = 26500
⇒ x = (26500 × 24) ÷ 125
⇒ x = 212 × 24 = ₹5,088
∴ The correct answer is ₹5,088.

Additional Information
Instalments in Simple Interest
When a debt D is to be paid in n equal annual instalments x at r% p.a., the formula is: D = n×x + [x × r × n(n−1)] ÷ 200.
Present Worth and True Discount
True Discount (TD) is the simple interest on the Present Worth (PW) of a debt due after a certain time. Due Amount = PW + TD. Also, PW = (Amount × 100) ÷ (100 + R×T).
Compound Interest Instalments
For Compound Interest, if a Principal P is repaid in n equal annual instalments x at rate R%, P = x ÷ (1 + R/100) + x ÷ (1 + R/100)2 + ... + x ÷ (1 + R/100)n.