A number multiplied by five times itself equals 1445. Form the equation n * (5n) = 1445 and determine the positive value of n.

Difficulty: Easy

Correct Answer: 17

Explanation:


Introduction / Context:
This algebraic simplification question checks your ability to translate an English statement into an equation and solve a simple quadratic for its positive root.



Given Data / Assumptions:

  • Statement: A number multiplied by five times itself equals 1445.
  • Let the number be n (assume n is real).
  • Equation: n * (5n) = 1445.


Concept / Approach:
Translate directly to an equation and solve for n. Since n * (5n) = 5n^2, isolate n^2 and take the positive square root (aptitude questions typically ask for the positive value unless specified otherwise).



Step-by-Step Solution:

From n * (5n) = 1445, we have 5n^2 = 1445.Divide both sides by 5: n^2 = 1445 / 5 = 289.Take square root: n = √289 = 17 (positive value).


Verification / Alternative check:
Compute 5n^2 with n = 17: 5 * 17^2 = 5 * 289 = 1445, which matches the given total exactly.



Why Other Options Are Wrong:
18, 15, 19, and 13 do not satisfy 5n^2 = 1445. Substituting any of these yields values other than 1445.



Common Pitfalls:
Interpreting “five times of itself” as n + 5n instead of n * (5n). The phrase clearly intends multiplication leading to 5n^2.



Final Answer:
17

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