UPSC Prelims 2016·CSAT·Quantitative Aptitude·Arithmetic

Two numbers X and Y are respectively 20% and 28% less than a third number Z. By what percentage is the number Y less than the number X ?

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Last updated 23 May 2026, 3:31 pm IST
  1. A12%
  2. B10%Correct
  3. C9%
  4. D8%

Explanation

Let the third number Z be 100. Step 1: Find the value of X. Since X is 20 percent less than Z, X = 100 minus 20 = 80. Step 2: Find the value of Y. Since Y is 28 percent less than Z, Y = 100 minus 28 = 72. Step 3: Calculate how much Y is less than X. The difference between X and Y is 80 minus 72 = 8. Step 4: Calculate the percentage. To find what percentage Y is less than X, divide the difference by X and multiply by 100. Percentage = (8 / 80) times 100. Percentage = 1/10 times 100 = 10 percent. Therefore, Y is 10 percent less than X. The correct option is B.
Quantitative Aptitude: Two numbers X and Y are respectively 20% and 28% less than a third number Z. By what percentage is the number Y less tha

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