Question

The masses of the oranges on sale at a farm stand are normally distributed with a mean of 239 grams and a standard deviation of 25 grams.
Enter the z-score of an orange that has a mass of 259 grams.

Update: The answer is 0.8

Answer 1

In order to calculate the z-score of a normal distribution, you need to apply the formula:

z = (o - m) / s

where:
o = observed value
m = mean
s = standard deviation

In your case:

z = (259 - 239) / 25 = 0.8

The answer is, indeed, z = 0.8