If data with a normal distribution has a mean of 100 and a standard deviation of 15, what is the probability of a value being greater than 110?

1 Answer
Bill K.
Oct 13, 2015

The probability is about 0.25=25%.

Explanation:

If you want to use a standard normal table, take x=110 and convert it to a z-score:

z=(x-mu)/sigma=(110-100)/15=10/15=2/3=0.666... approx 0.67

Next, use a standard normal table to say:

P(X>110) = P(Z> 0.67) approx 0.25=25%

You might also be able to use your calculator to confirm this without converting to a z-score.

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