The average electricity bill for Lynn’s home is $64.50 per month with a standard deviation of $8.20. In June she received a bill of only $30.00 because she was traveling for most of the month. How many standard deviations below the mean is the amount of Lynn’s electricity bill for June?

This bill is about 4.21 standard deviations below the mean value.

To find this, first subtract the mean from the given amount.

30 - 64.5 = -34.5

Now, divide this by 8.2, which is the amount of 1 standard deviation.

34.5 / 8.2 = 4.21

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ApusApus ApusApus · Answer 2 · 2019-05-31T18:57:24+02:00

Answer:

4.21 standard deviation below mean.

Step-by-step explanation:

We have been given that the average electricity bill for Lynn’s home is $64.50 per month with a standard deviation of $8.20. In June she received a bill of only $30.00.

We will use z-score formula to solve our given problem.

[tex]z=\frac{x-\mu}{\sigma}[/tex], where,

[tex]z=\text{z-score}[/tex],

[tex]x=\text{Sample-score}[/tex],

[tex]\mu=\text{Mean}[/tex],

[tex]\sigma=\text{Standard deviation}[/tex]

Upon substituting our given values in z-score formula we will get,

[tex]z=\frac{30-64.50}{8.20}[/tex]

[tex]z=\frac{-34.5}{8.20}[/tex]

[tex]z=-4.2073170731\approx -4.21[/tex]

Since z-score is negative, therefore, the amount of Lynn’s electricity bill for June is approximately 4.21 standard deviations below mean.