Profit and Loss – Tiered discounts over multiple car services in a year: Base servicing charge is ₹ 400. The second service within the year gets a 10% discount. The third and fourth services each cost 10% less than the immediately previous amount paid. From the fifth service onward within the year, a customer pays 60% of the full servicing charge per service. If a customer avails 5 services in the year, what total percentage discount does he receive compared to paying full price for all 5?

Introduction / Context:
This question features a staircase of discounts across services within a single year. We must carefully interpret the policy: a fixed base price, a one-time 10% discount on the second service, successive 10% reductions relative to the immediately previous amount paid for the third and fourth, and from the fifth service onward a flat 60% of the full charge per service.

Given Data / Assumptions:

• Base charge per service = ₹ 400
• Second service = 10% off 400 ⇒ ₹ 360
• Third service = 10% less than previous amount paid ⇒ 10% off 360 ⇒ ₹ 324
• Fourth service = 10% less than previous amount paid ⇒ 10% off 324 ⇒ ₹ 291.60
• Fifth service = 60% of full charge ⇒ 0.60 * 400 = ₹ 240

Concept / Approach:
Compute the total actually paid for 5 services and compare with the full-price total (5 * 400). The discount percentage equals (Full − Paid) / Full * 100.

Step-by-Step Solution:
Full-price total = 5 * 400 = ₹ 2000Actual paid = 400 + 360 + 324 + 291.60 + 240 = ₹ 1615.60Total discount = 2000 − 1615.60 = ₹ 384.40Discount% = 384.40 / 2000 * 100 = 19.22% ≈ 19.2%

Verification / Alternative check:
Rounding the fourth service to ₹ 292 changes the final by less than 0.02 percentage points; 19.2% remains the correct rounded choice to one decimal place.

Why Other Options Are Wrong:
18.5% and 17.6% are too low; 26% is far too high; 21% overshoots the computed value.

Common Pitfalls:
Misreading “10% of the previous amount paid” as “10% of the original ₹ 400” for services 3 and 4, or mishandling the 60% rule from the fifth service.

Final Answer:
19.2%