Statistics Utility

Write a Statistics class that has the following static methods:

• sampleSize(double[] arr) - returns the number of values in the array
• maximum(double[] arr) - identifies and returns the largest value in the array
• minimum(double[] arr) - identifies and returns the smallest value in the array
• mean(double[] arr) - calculates and returns the mean (average) of the values in the array
• median(double[] arr) - calculates and returns the middle value in the array after it has been sorted.
  • Note that in the case of an even number of values, the median value is calculated as the mean of the two middle numbers in the sorted array.
  • Note that you may use the Arrays.sort(arr) method to sort your array for this method. You'll need to import java.util.Arrays to use that static method.
  • Note that YOU MUST NOT SORT THE ORIGINAL ARRAY! That would be a side effect--we shouldn't alter the original array of values. Instead, make a copy of the original array in your method and sort/analyze that copy.
• mode(double[] arr) - returns the value that occurs most frequently in the array of values.
  • Although it's possible to have more than one mode for a given array of numbers, your method won't be given data to test that situation, and you don't need to test for it.
  • If no value appears more than once, this method should return null. Because we want to return a null value, and this can only correspond with objects, the return type of this method should be a Double, the wrapper class for double objects.

The following Arrays can be used to test your class:

arr = {1, 0, 3, 8, 4, 2, 1, 9, 20, 100}
sampleSize(arr) --> 10
maximum(arr) --> 100
minimum(arr) --> 0
mean(arr) --> 14.8
median(arr) --> 3.5
mode(arr) --> 1

arr = {2, 3, 2, 3, 2, 17, -5}
sampleSize --> 7
maximum --> 17
minimum --> -5
mean --> 3.4285714285714284
median --> 2.0
mode --> 2.0

arr = {1, 2, 3, 4, 5}
mode --> null