# Statistics

posted by Stuart

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

1. MathGuru

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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