Maths question from Jr. Assistant exam, 2026 by JKSSB
If a discount 10% given on the marked price of a book, the publisher gains 20%. If a discount is increased to 15%, the gain of the publisher is?
Last updated May 13, 2026
Correct Answer:
Option B —
13 1/3%
To solve this, it is easiest to assign a starting number for the Marked Price (the price printed on the book) and work through the relationships between the cost, the discount, and the profit.
Step 1: Find the Cost Price
Imagine the Marked Price of the book is 100.
First Scenario: A 10 percent discount is given. This means the book is sold for 90.
At this selling price of 90, the publisher is still making a 20 percent gain.
This means the 90 represents 120 percent of the original cost. To find the cost, we determine what number, when increased by 20 percent, equals 90.
By calculating this, we find the Cost Price is 75. (Since 20 percent of 75 is 15, and 75 plus 15 equals 90).
Step 2: Apply the New Discount
Second Scenario: The discount is increased to 15 percent.
We take that original Marked Price of 100 and subtract 15 percent.
The New Selling Price is 85.
Step 3: Calculate the New Gain
Now we compare the new selling price (85) to our original cost (75).
The profit in money is 85 minus 75, which equals 10.
To find the gain percentage, we look at what portion 10 is of the cost price (75).
10 divided by 75 simplifies to 2 over 15.
Converting the fraction 2 over 15 into a percentage gives us 13 and 1 over 3 percent.
Answer verified by Quintessence Classes faculty — Karan Nagar, Srinagar.
