Mills Ratio in probability and statistics

What is the Mills Ratio in probability and statistics? How can it be Used to find accurate bounds and approximations to standard normal cdfs for values of z ‘off the chart’? Write a four or five page report on this. Compute at least three different approximations of Mills Ratio forz = 3,5,10,20. (One of these may be discussed in class later). Cite at least three references, including one one book or research article.(| can suggest some references, if you can’t find any).