## anonymous one year ago The score on the statistics class final exam follow normal distribution with a mean of 80 and a standard deviation of 5. What percent of students scored 90 or better ?

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1. anonymous

$P(X\ge90)=P\left(\frac{X-80}{5}\ge\frac{90-80}{5}\right)=P(Z\ge2)$ You can use this rule to quickly compute the proportion: http://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule