Quote Of The Day

"Victory goes to the player who makes the next-to-last mistake - Chessmaster Savielly Grigorievitch Tartakower (1887-1956)"

Friday, June 15, 2007

Brain teaser answer...
240mph

Distance = speed x time

Average speed over = s1 = 696
Average speed back = s2 = 145

So if time over is t1 and time back is t2 then distance = s1 x t1 = s2 x t2

Total average speed = (2 x distance)/(t1 +t2) = (2 x s2 x t2)/(t1 + t2) = (2 x s2)/(t1/t2 + 1) = (2 x s2)/(s2 / s1 + 1) = (2 x s2 x s1)/(s2 + s1) = (2 x 145 x 696)/(145 + 696) = 240

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