Question

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?

Answer 1

Answer:

The z-score is  $z = 2.65$

The length of days is not unusual

Step-by-step 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

           $z = \frac{x - \mu}{\sigma }$

            $z = \frac{309 - 267.6}{15.6 }$

           $z = 2.65$

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)