Unable to solve (Gamma Distribution)

[euler_fan]

I am using the following web page for reference. At this point I am not sure how $637 was found to be the value of payments less than 5% and $1444 the value of payments greater than 5%. I would greatly appreciate any hint!


http://www.brighton-webs.co.uk/distributions/gamma.asp [Broken]

 

[HallsofIvy]

???? Those are given as parameters in the problem.


If I tell you I purchased something with a price tag of $75 at a 10% discount, and asked how much I actually paid, would you ask how I got the $75 and 10%?