Question

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
• E. 260.15

Answer 1

The correct option is A

14.5

Let the number be x.

Then, $\frac{3}{5}{x}^2=126.15\iff x^2=\left(126.15\times \frac{5}{3}\right)=210.25\iff x=\sqrt{210.25}=\mathrm{14.5.}$