This week on Car Talk, trucker Richard has a busted fuel gauge in his 18-wheeler. He's got a trusty stick to help measure the level of fuel in his cylindrical tank, but needs a formula to tell him whether that level means he's got 3/4 of a tank, or is running on fumes. You'd think two MIT grads would be able to help, but, well, you'd be wrong.
OK my smart friends, the tank measures 18 inches in diameter. Obviously when you dip the ruler into the tank you know that at 9 inches it means it's half full. What mark on the ruler would tell you the tank was one quarter full?
I came up with 7.1 inches. I used only geometry and as usual I did it in my head and can't explain exactly how I got my answer except I compared the area of an 18 inch square with an 18 inch circle. So, my smart friends, help me out. Tell me if I'm right because the problem with having Aspergers is that even when you don't want it, it's always there.
Remember, no calculus, no trig, no sliderulers, just a simple calculator.