Question 1186998: According to the Internal Revenue Service, income tax returns one year averaged $1,332 in refunds for taxpayers. One
explanation of this figure is that taxpayers would rather have the government keep back too much money during the
year than to owe it money at the end of the year. Suppose the average amount of tax at the end of a year is a refund of
$1,332 with a standard deviation of $725.
a) What proportion of tax returns show a refund greater than $1,900?
b) What proportion of the tax returns show that the taxpayer woes money to the government?
c) What proportion of the tax returns show a refund between $200 and $800?
d) Examine by the diagram.
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! z=(x-mean)/sd
z>(1900-1332)/725 =0.78
that probability is 0.2177
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z< (-1332/725) =-1.84, and the probability of that is 0.0331
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for 200, z=-1132/725 or -1.561
for 800, z=-532/725 or -0.734
The probability of z being between those two is 0.1722
On a calculator, 2ndVARS2 normalcdf(200,800,1332,725) ENTER
ask how much the teacher wants the z-value rounded to. It will change the result slightly.
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