Sorting Question

Assume that a merge sort algorithm in the worst case takes 30 seconds for an input of size 64. Which of the following most closely approximates the maximum input size of a problem that can be solved in 6 minutes?

Whats the answer and explanation?

hi ishwar
Time complexity of merge sort is Θ(nLogn)

c64Log64 is 30
c
64*6 is 30
c is 5/64

For time 6 minutes

5/64nLogn = 660

nLogn = 72*64 = 512 * 9

n = 512.