Quantitative Methods

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The monthly income of residents of Daisy City is normally distributed with a mean of $3000 and a standard deviation of $500.
a. What is the random variable?
b. The mayor of Daisy City makes $2250 a month. What percentage of Daisy City's residents has incomes that are more than the mayor?
c. Individuals with incomes of less than $1985 per monthe are exempt from city taxes. What percentage of residents is exempt from city taxes.
d. What are the minimum and the maximum incomes of the middle 95% of the residents
e. Two hundred residents have incomes of at least $4440 per month. What is the population of Daisy City.

I am using z= x-the mean/sd but i am not getting a correct answer.

  • Quantitative Methods -

    I find this page very useful for these kind of problems.

    http://davidmlane.com/hyperstat/z_table.html

    The beauty is that you don't even have to enter the z-scores (you can of course), but rather enter the mean and SD directly.

    Since these kind of question rely on the use of tables or charts, I don't see any difference in using tables or a new type of application as this applet.
    Let me know how it works for you

    BTW, bobpursley answered the post just below this one for you yesterday.

  • Quantitative Methods -

    i used the site (thx a bunch) but after i get the area i am confused as to how i get the final answer? the area for b is .066807 but i am not sure what to do next

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