A bottler of drinking water fills plastic bottles with a mean volume of 1,007 milliliters (mL) and standard deviation The fill volumes are normally distributed. What proportion of bottles have volumes less than 1,007 mL?

Respuesta :

Answer:

0.5 = 50% of bottles have volumes less than 1,007 mL

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this question, we have that:

[tex]\mu = 1007[/tex]

What proportion of bottles have volumes less than 1,007 mL?

This is the pvalue of Z when X = 1007. So

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{1007 - 1007}{\sigma}[/tex]

[tex]Z = 0[/tex]

[tex]Z = 0[/tex] has a pvalue of 0.5

0.5 = 50% of bottles have volumes less than 1,007 mL