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dvitalo
Sep 24, 2009, 05:34 PM
With a mean of 69 mph and a SD of 12.6 mph, what percentage of cars were travelling at 60 mph or slower?

galactus
Sep 26, 2009, 11:22 AM
Just use the formula z=\frac{x-{\mu}}{\sigma}

z=\frac{60-69}{12.6}

Look up the corresponding value in a z table.