Question

In Haskell programming language
(1) Write a "averageThree" function to return the average of three integers.
averageThree :: Integer -> Integer -> Integer -> Float

(2) Write a "howManyAboveAverage" function which returns how many of three integer inputs are above its average value. (utilize the averageThree function.)
howManyAboveAverage :: Integer -> Integer -> Integer -> Integer

(3) Write a "howManyWithinThreshold" function that returns how many of the first three arguments are within the threshold (the fourth argument) of the average of the first three arguments. (utilize the averageThree function and the logic in the howManyAboveAverage function.)
howManyWithinThreshold :: Integer -> Integer -> Integer -> Float -> Integer

I personally have completed (1) and (2)!

[sample of (1)]
averageThree :: Integer -> Integer -> Integer -> Float
averageThree a b c = (fromIntegral (a + b + c)) / 3

All i need help with is 3, where i am stuck and can not resolve!

Answer 1

Source Code:

module main where

--averageThree to return the average of three integers
averageThree :: Integer -> Integer -> Integer -> Float
averageThree x y z = fromInteger(x*y*z)/3

--howManyAboveAverage that returns how many of three integer inputs are above its average value
howManyAboveAverage :: Integer -> Integer -> Integer -> Integer
howManyAboveAverage x y z
| x > round(averageThree x y z) && y > round(averageThree x y z) = 2
| y > round(averageThree x y z) && z > round(averageThree x y z) = 2
| x > round(averageThree x y z) && z > round(averageThree x y z) = 2
| x==y && y==z = 0
| otherwise = 1

--howManyWithinThreshold that returns how many of the first three arguments are within the threshold
--(the fourth argument) of the average of the first three arguments.
howManyWithinThreshold :: Integer -> Integer -> Integer -> Float -> Integer
howManyWithinThreshold w x y z
| ((averageThree w x y)-z) < fromInteger(x) && ((averageThree w x y)+z) > fromInteger(x) && ((averageThree w x y)-z) < fromInteger(y) && ((averageThree w x y)+z) > fromInteger(y) && ((averageThree w x y)-z) < fromInteger(w) && ((averageThree w x y)+z) > fromInteger(w) = 3
| ((averageThree w x y)-z) < fromInteger(x) && ((averageThree w x y)+z) > fromInteger(x) && ((averageThree w x y)-z) < fromInteger(y) && ((averageThree w x y)+z) > fromInteger(y) && ((averageThree w x y)-z) > fromInteger(w) || ((averageThree w x y)+z) < fromInteger(w) = 2
| ((averageThree w x y)-z) < fromInteger(x) && ((averageThree w x y)+z) > fromInteger(x) && ((averageThree w x y)-z) > fromInteger(y) || ((averageThree w x y)+z) < fromInteger(y) && ((averageThree w x y)-z) < fromInteger(w) && ((averageThree w x y)+z) > fromInteger(w) = 2
|((averageThree w x y)-z) > fromInteger(x) || ((averageThree w x y)+z) < fromInteger(x) && ((averageThree w x y)-z) < fromInteger(y) && ((averageThree w x y)+z) > fromInteger(y) && ((averageThree w x y)-z) < fromInteger(w) && ((averageThree w x y)+z) > fromInteger(w) = 2
|((averageThree w x y)-z) < fromInteger(x) && ((averageThree w x y)+z) > fromInteger(x) && ((averageThree w x y)-z) > fromInteger(y) || ((averageThree w x y)+z) < fromInteger(y) && ((averageThree w x y)-z) > fromInteger(w) || ((averageThree w x y)+z) < fromInteger(w) = 1
|((averageThree w x y)-z) > fromInteger(x) || ((averageThree w x y)+z) < fromInteger(x) && ((averageThree w x y)-z) < fromInteger(y) && ((averageThree w x y)+z) > fromInteger(y) && ((averageThree w x y)-z) > fromInteger(w) || ((averageThree w x y)+z) < fromInteger(w) = 1
|((averageThree w x y)-z) > fromInteger(x) || ((averageThree w x y)+z) < fromInteger(x) && ((averageThree w x y)-z) > fromInteger(y) || ((averageThree w x y)+z) < fromInteger(y) && ((averageThree w x y)-z) < fromInteger(w) && ((averageThree w x y)+z) > fromInteger(w) = 1
| otherwise = 0

Hope this helps!