An article is sold for ₹747 after successive discounts of 17% and x%. If the marked price of the article is₹1,600, what is the value of x?
- (a)40.28
- (b)32.26
- (c)43.75
- (d)22.12
Answer
Why
Correct — C. Marked price ₹1,600, first discount 17%, second discount x%, selling price ₹747.
After the first discount:
1600 × (100 − 17)⁄100 = 1600 × 0.83 = ₹1,328
The second discount acts on ₹1,328, not on ₹1,600:
1328 × (100 − x)⁄100 = 747
(100 − x)⁄100 = 747⁄1328 = 0.5625
100 − x = 56.25
x = 43.75 → option (c)
Why the others are wrong
- (a)40.28 — Substituting x = 40.28 gives 1328 × 0.5972 ≈ ₹793, well above the ₹747 the stem states. Any second discount smaller than 43.75% leaves too much price standing.
- (b)32.26 — x = 32.26 gives 1328 × 0.6774 ≈ ₹899.59. The stem fixes the selling price at ₹747, which is under half the marked price, so a second cut this small cannot reach it.
- (d)22.12 — x = 22.12 leaves 1328 × 0.7788 ≈ ₹1,034, nowhere near ₹747. Falling from ₹1,600 to ₹747 is a drop of 53.31%, and 17% with 22.12% compound to only about 35%.
Concept
Successive discounts compound downwards: the second is taken on what survives the first, never on the marked price.
Two equivalent routes. Multiply the survival fractions, 1600 × 0.83 × (1 − x⁄100) = 747.
Or use the single-equivalent form: discounts of a% and b% together equal a + b − ab⁄100 per cent.
Here the total drop is (1600 − 747)⁄1600 = 53.3125%, and that is not 17 + x. Adding the two rates instead of compounding them is the standard slip: 17 + 43.75 = 60.75, not 53.31.
The numbers are cleaner as fractions. 747⁄1328 reduces to 9⁄16 because both are multiples of 83, so the second survival fraction is exactly 0.5625 and x = 43.75 with no decimal work at all.
Key facts
- Two successive discounts of a% and b% equal a single discount of a + b − ab⁄100 per cent.
- 17% and 43.75% combine to 17 + 43.75 − 7.4375 = 53.3125%, and 1600 × (1 − 0.533125) = 747.
- The second discount is computed on the reduced price ₹1,328, not on the marked price ₹1,600.
- 747⁄1328 = 9⁄16 = 0.5625, so the second discount is 43.75%.
Study next
Common traps
- Applying the second discount to ₹1,600 instead of to ₹1,328.
- Adding 17 and x to match the 53.31% total drop, which returns 36.31 rather than 43.75.
- Rounding 0.5625 to 0.56 early, which shifts x to about 44 and off the option list.
SSC runs successive discounts in both directions. Given both rates and asked for the price: 23 Sep 2024, 12:30, Quant Q.11. Given the price and one rate and asked for the missing rate, as here: 18 Sep 2024, 12:30, Quant Q.3.
Related PYQs
No directly related past PYQ was found.