
Why?
We have the isosceles right triangle. The length of legs are 6. Use the Pythagorean theorem:

In general, the formula for calculating the hypotenuse in an isosceles right triangle is 
a - a leg, h - a hypotenuse
A. 485 is %3 of 500, but the deviation sets it slightly lower than that
<span>√63 = 3√7 is your answer</span>