2015 · Q9
A student was asked to multiply a number by 25. He instead multiplied the number by 52 and got the answer 324 more than the correct answer. The number to be multiplied was
Elementary MathematicsNumber System
- A12
- B15
- C25
- D32
Explanation
This is a one-variable linear equation problem. Let the number be n: the student computed 52n instead of 25n, and the excess over the correct answer is 52n - 25n = 27n = 324, so n = 12. Checking: 52 × 12 = 624 versus 25 × 12 = 300, a difference of exactly 324. The key step is translating "324 more than the correct answer" into the subtraction 52n - 25n. Hence option (a).