If average of a number, 50% of the number and 25% of the number is 280, then the number is

Let the number be x. Its average with 50% of x and 25% of x is (x + 0.5x + 0.25x)/3 = 280. So 1.75x = 840, which gives x = 480. Option B is correct.

Check: 480, 240 and 120 add up to 840, and 840/3 = 280.

• A (280): The three values are 280, 140 and 70, with an average of about 163. Wrong.
• C (360): The three values are 360, 180 and 90, with an average of 210. Wrong.
• D (None of the above): Incorrect, because B satisfies the condition.

Core concept: turning 'x% of a number' into a fraction and setting up a linear equation. It is basic arithmetic, but the same habit of translating words into equations carries into the averages and percentages questions in CSAT and data interpretation.

Trap: forgetting to divide the total by 3 for the average, or reading 25% as 0.25 times the average. Substituting the options back into the stated condition is the quick check.