Posted by **Stuart** on Sunday, February 22, 2009 at 4:06pm.

In 2020, the average charge of tax preparation was $95. Assuming a normal distribution and a standard deviation of $10, use the approximate areas beneath the normal curve, as discussed in this section, to answer the following questions.

What proportion of tax preparation fees were between $75 and $115?

A) 0.84

B) 0.34

C) 0.955

D) 0.75

- Statistics -
**MathGuru**, Sunday, February 22, 2009 at 9:48pm
This will be within two standard deviations of the mean. To show this, use z-scores.

Formula is this:

z = (x - mean)/sd

Therefore:

z = (75 - 95)/10 = ?

z = (115 - 95)/10 = ?

I'll let you finish the calculations. Remember that one z-score is below the mean and one is above the mean.

I hope this will help get you started.

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