How do I answer this using excel? According to the IRS the mean tax refund for t

ID: 3130711 • Letter: H

Question

How do I answer this using excel?

According to the IRS the mean tax refund for the year 2009 was $3333

The standard deviation of the population of returns is $551, and the amounts follow the normal distribution

What percent of the returns are between $3000 and $5000?

How do I answer this using excel?

According to the IRS the mean tax refund for the year 2009 was $3333

The standard deviation of the population of returns is $551, and the amounts follow the normal distribution

What percent of the returns are between $3000 and $5000?

For X1=3000, z1=(x-mu)/sigma=(3000-3333)/551

=-0.6

For X2=5000, z2=(5000-3333)/551=3.02

Thus, P(3000<X<5000)

=P(X2<5000)-P(X1<3000)

=P(z2<3.02)-P(z1<-0.6)

=0.9987-0.2743

=0.7244

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