the answer of 6.37 maybe wrong

[sttttwv]

N=64, sumB
The size of array is four times of cache's, that means every sixteen rows in the array are mapped to the same row in the cache, for example the row 0, 16, 32, 48 would be mapped to the first row of cache. After the first inner loop is completed, the data in cache is the first four numbers of lines 48 to 63. If search the number in lines 0 to 15, it will be missed. So the miss rate is 100%.

[sttttwv]

N=64, sumC
I think the answer is 50%.

[AE-GG]

My answer is same to you.

Function	$N=64$	$N=60$
sumA	$25 %$	$25 %$
sumB	$100 %$	$100 %$
sumC	$50 %$	$50 %$