# SOLUTION: A normal distribution of weekly income has a mean of \$250 and a standard deviation of \$20. Approximately what proportion of people earn between \$240 and \$260 a week?

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 Click here to see ALL problems on Probability-and-statistics Question 414490: A normal distribution of weekly income has a mean of \$250 and a standard deviation of \$20. Approximately what proportion of people earn between \$240 and \$260 a week?Answer by stanbon(57984)   (Show Source): You can put this solution on YOUR website!A normal distribution of weekly income has a mean of \$250 and a standard deviation of \$20. Approximately what proportion of people earn between \$240 and \$260 a week? ----- z(240) = (240-250)/20 = -1/2 --- z(260) = (260-250)/20 = +1/2 ---- Proportion(240<= x <=260) = P(-1/2 <= z <=1/2) = 0.3829 ==================== Cheers, Stan H.