Question

When Stephan moved from Illinois to Florida, his average monthly electric bill increased from $83 to $102. He is curious to know whether his IL or FL electric bill is relatively more or less expensive, when compared to the distribution of electric bills for each state. In Illinois, the mean monthly electric bill is $85, with a standard deviation of $3.20. In Florida, the mean monthly electric bill is $105, with a standard deviation of $4.00. Compute the z-scores for Stephan's IL and FL electric bills. Round to three decimal places if necessary.

Answer 1

Answer: The z-scores for Stephan's IL and FL electric bills. are -0.625 and 0.75 respectively.

Step-by-step explanation:

Given:  Average monthly electric bill in Illinois =  $83

Average monthly electric bill in Florida = $102

Formula of z : $z=\dfrac{X-mean}{standard\ deviaton}$

In Illinois, the mean monthly electric bill is $85, with a standard deviation of $3.20.

$z=\dfrac{83-85}{3.20}= -0.625$

In Florida, the mean monthly electric bill is $105, with a standard deviation of $4.00.

$z=\dfrac{105-102}{4}=\dfrac{3}{4}=0.75$

Hence, the z-scores for Stephan's IL and FL electric bills. are -0.625 and 0.75 respectively.