A dress is marked at ₹3,500. A discount offer changes from 10% to 15%. How much extra discount does a customer get?

Correct — A.
Discount at 15% = 15% × 3500 = ₹525
Discount at 10% = 10% × 3500 = ₹350

Extra discount = 525 − 350 = ₹175
Shortcut: (15 − 10)% × 3500 = 5% × 3500 = ₹175 → option (a).

Why the others are wrong

• (b)
  ₹185 — ₹185 is about 5.29% of ₹3,500, not 5%. Both discounts are taken on the same marked price, so the extra is exactly 5% of ₹3,500, which is ₹175.
• (c)
  ₹195 — ₹195 is about 5.57% of ₹3,500. The offer moves from 10% to 15% of one marked price, a 5-point change worth exactly ₹175.
• (d)
  ₹200 — ₹200 is 5% of ₹4,000, not of ₹3,500. The dress is marked at ₹3,500, and 5% of that is ₹175.

When two discounts are both taken on the same marked price, the gap in rupees is the gap in percentage points applied to that price.

Here 15% − 10% = 5 points, and 5% of ₹3,500 is ₹175. Neither selling price has to be worked out.

This is different from successive discounts, where the second percentage is taken on a price already reduced by the first.

Key facts

• Discount = discount % × marked price.
• Two flat discounts on one marked price differ by (difference in %) × marked price.
• At 10% off the dress sells for ₹3,150 and at 15% off for ₹2,975, a gap of ₹175.

Common traps

• Taking the extra 5% on the already discounted ₹3,150, which gives ₹157.50.
• Answering with the new discount, ₹525, when the stem asks for the extra discount.

No directly related past PYQ was found.