Question 1171892
the mean is 55000.
the standard deviation is 4500.
the following calculator should help you answer these questions.
<a href = "http://davidmlane.com/hyperstat/z_table.html" target = "_blank">http://davidmlane.com/hyperstat/z_table.html</a>
the answers to your questions are shown below:


a. What is the probability that a randomly selected household will have an income between $50,000 and $65,000? (2 Marks)


probability is .8536


<img src = "http://theo.x10hosting.com/2020/122701.jpg" >



b. What is the probability that a randomly selected household will have an income of more than $70,000? (2 Marks)


probability is .0004


<img src = "http://theo.x10hosting.com/2020/122702.jpg" >



c. What minimum income does a household need to earn to be in the top 5% of incomes?(2 Marks)


minimum income is 62401.842


<img src = "http://theo.x10hosting.com/2020/122703.jpg" >



d. What maximum income does a household need to earn to be in the bottom 40% of incomes? (2 Marks)


maximum income is 53859.938


<img src = "http://theo.x10hosting.com/2020/122704.jpg" >


i verified with the ti-84 plus that these answers are correct.


if you need to know how to do these manually through the use of the normal distribution tables, all you have to do is ask.


i can do them that way as well.
it just takes a little longer.
maybe even a little longer than that.