Question

You take random sample of 200 people from Salinas and find that their average income is $48,000 per year
with a standard deviation of $9000. Also assume that population incomes are normally distributed.
Approximately how many people make between $39,000 and $57,000?
X
Answer format: Enter a positive integer

Answer 1

We have that  The Total Number of People is

$X\approx 137$

From the question we are told that

sample of 200

income is $48,000 per year

standard deviation of $9000

Generally the equation for the Ratio of people  is mathematically given as

$Y=P(\frac{39000-48000}{9000}<z<\frac{57000-48000}{9000})\\\\\Y=P(z<1))-(1-p(z-1))\\\\Y=0.8413-0.1582\\\\\Y=0.6826$

Therefore

The Total Number of People is

$X=0.6826*200\\\\X\approx 137$

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