In the cache, there will be 4 blocks as 1 block=16 words. Now In main memory, we will require 100 blocks to hold the 200 elements of the array. Further, In one block there can be two elements present.
And each element of the array is referred two times.
At first, it will generate miss for A[0] while reading the value of A[0] but when it comes to writing its value, the reference will be a hit as the element is already present in the cache. For A[1] both for reading and writing it will be a hit coz it is already in cache because it was present in the same block as that of A[0].
So For each block, there will be 3 hits and 1 miss
hit ratio=total hits/total references
=(3*100)/2*200
=0.75