You should be proud of yourself.  You got further on this test than most people, but that was a tough question.  You had to use the metric system and the Pythagorean Theorem.  The correct answer was 60 centimeters.

I recommend reading Volume 4 of the Learn Math Fast System.  At your level, you could complete that short book in less than a month.  Thanks for taking our Placement Test.  Use coupon code PT2026 to get 10% off your order.