gistfile1.hs

{-
Income quintiles in 2011. This represents the poorest fifth to the richest fifth
of income earners in america in 2001.
-}

income2011 = [15282.0, 37556.0,  61032.0, 93232.0, 197932.0]

{-
Find the average income of americans, by averaging the quintiles.

Useful functions:
  * sum: takes a list of numbers and returns their sum.
  * length: takes a list and returns its length, obviously.
-}

myAverage x = sum x / (realToFrac (length x))

{-
Find the ratio between the highest fifth and the lowest fifth of the income earners for 2011.

useful functions:
  * head: get the first element of a list
  * last: get the last element of a list
-}

disparity2011 = (last income2011) / (head income2011)

{-
Prelude> disparity2011
12.951969637482005

That is, the richest fifth made 13 times more than the poorest fifth in 2011.

Write a function that does that given any year
-}

richPoorRatio y = (last y) / (head y) 

{-
find out how much ratio of incomes between the highest fifth and the lowest fifth has changed from 1966 to 2011.
-}

income1966 = [2345.0, 5206.0, 7449.0, 9972.0, 17019.0]

changeFrom1966to2012 = richPoorRatio income2011 / richPoorRatio income1966

{-
Prelude> changeFrom1966to2012
1.784615359298155

Income disparity has increase 78% in the last 44 years
-}