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Lengths of pregnancies​ (in humans) have a mean of 267.6 days and a standard deviation of 15.4 days. A woman tracked her pregnancy and found it to be 309 days. Find the z score for 309 days. Is such a length​ unusual?

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Answer:

The z-score is
z = 2.65

The length of days is not unusual

Explanation:

From the question we are told that

The population mean is
\mu = 267.6 \ days

The standard deviation is
\sigma = 15.4 \ days

The value considered is
x = 309 \ days

The z-score is mathematically represented as


z = (x - \mu)/(\sigma )


z = (309 - 267.6)/(15.6 )


z = 2.65

Now given that the z-score is not greater than 3 then we can say that the length of days is not unusual

(reference khan academy)

User Surya Chereddy
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