Wednesday, July 20, 2011

PUZZLE: Tabling the Question

I haven't done a math puzzle in a while, so here's an old one to strain the average brain. (And by that I mean my brain: in the past, my readers have solved these so fast it's almost embarrassing.)

Mr. Jenkins comes home to find his son Todd reading a comic book rather that working on his quadratic equations. He sets about berating the boy, when Todd interrupts him with a deal. "If I can pose a problem you can't solve, you have to finish my homework, and I can to finish my comic." Mr. Jenkins, considering himself something of a math whiz, takes this bet in a heartbeat.

Todd pushes a large, perfectly round table into a corner, with its edge touching both walls. He places a spot and then turns to his father. "That spot," says Todd, "is exactly 9 inches from one wall and 8 inches from the other. Without measuring the table, tell me its diameter."

My Jenkins puzzled and puzzled 'til his puzzler was sore, and then wound up finishing Todd's homework while the boy returned the adventures of Uncle Scrooge. Would you have done any better?


Todd Neller said...

(Clarification: The spot is on the table's edge.)

Joshua Fahey said...

I think I could solve the quadratic equations...

Bruce said...

58 inches (10 inches wouldn't be much of a table)

(x-8)^2 + (x-9)^2 = x^2, where x = radius

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