From the given numbers, find a positive number which, when increased by 17, is equal to 60 times the reciprocal of the number.
- 20
- 6
- 4
- 3
- 9
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Answer: D official key
Approach: Form the equation x + 17 = 60/x and solve the quadratic.
Solution:
x + 17 = 60/x → x² + 17x − 60 = 0.
(x + 20)(x − 3) = 0 → x = 3 or x = −20.
Positive number = 3.
Check: 3 + 17 = 20 = 60/3. ✔
Cetking shortcut: Plug options: only 3 gives 20 on both sides (20 → 37 vs 3; 6 → 23 vs 10; 4 → 21 vs 15).
Answer: D