The amount of Jen's monthly phone bill is normally distributed with a mean of $55 and a standard deviation of $8.Draw and label the Normal model for Jen's monthly phone bill.In what interval would you expect the central 68% of bills to be found?
A) ; $31 to $79
B) ; $39 to $71
C) ; $47 to $71
D) ; $47 to $63
E) ; $39 to $63

Question

The amount of Jen's monthly phone bill is normally distributed with a mean of $55 and a standard deviation of $8.Draw and label the Normal model for Jen's monthly phone bill.In what interval would you expect the central 68% of bills to be found?
A) ; $31 to $79 
B) ; $39 to $71 
C) ; $47 to $71 
D) ; $47 to $63 
E) ; $39 to $63

Quizplus · Accepted Answer

To draw the Normal model, we use the mean of $55 as the center and the standard deviation of $8 to determine how spread out the distribution is. We can label the model as follows:

Mean = $55
Standard deviation = $8

Using the Empirical Rule, we know that approximately 68% of bills will be within 1 standard deviation of the mean. Therefore, we can estimate the interval for the central 68% as follows:

Lower bound = $55 - $8 = $47
Upper bound = $55 + $8 = $63

So, the best choice is D, which corresponds to $47 to $63 as the interval for the central 68% of bills.

The Amount of Jen's Monthly Phone Bill Is Normally Distributed