The monthly income of residents of Daisy City is normally distributed with a mean of $3000 and a standard deviation of $500.

Question

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.

Answer 1

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.

Answer 2

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