Main thread randomly generates an array of double values with a given size $($say$,$ N$=1000),$ and divides it into two smaller arrays of equal size. It then passes each sub$-$array to sorting$\_$avg thread $($creates two copies of the same thread$),$ and waits until these two sub$-$arrays are sorted and the average of the values in each array are computed. It then calls merging$\_$avg thread by passing the already sorted two sub$-$arrays, and the averages of the first and second sub$-$arrays as parameters.

Sorting$\_$avg thread sorts the given sub$-$array using insertion sort or selection sort $($one is enough and you need to implement either one$),$ and computes the average of the values in the given array. So this thread returns sorted sub$-$array and its average.

Merging$\_$avg thread takes both sorted sub$-$arrays and the their averages as parameters. It then merges them into a single sorted array in a linear time $($so don't call sorting function again! You can simply have a loop and take the smallest from the sorted arrays until they are all merged!$),$ and simply find the overall average by taking the average of the given two averages $($this will work because we assume both sub$-$arrays have the same size!$).$