Subject: General Aptitude · Chapter: Square Roots and Cube Roots · Exam: · Marks: · Difficulty:
Three-fifth of the square of a certain number is 126.15. What is the number?
(a)14.5
(b)75.69
(c)145
(d)210.25
Answer
Answer (as printed): A
Explanation
Let the number be $x$. Then, $$\begin{aligned} & \frac{3}{5} x^{2}=126.15 \Leftrightarrow x^{2}=\left(126.15 \times \frac{5}{3}\right)=210.25 \\ & \Leftrightarrow x=\sqrt{210.25}=14.5 . \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.