This is how 2 do this

programming
Tags: #<Tag:0x00007f24277418d0>

#1

So lets say it will take N days. 1/3 of the cases are done in 0 days as before. 1/3 of the cases are 1+N. 1/3 are 2 + N.

N = 1/3 * 0 + 1/3 * (1 + N) + 1/3 * (2 + N)
N = 1 + 2N/3
Therefore, N/3 = 1 ; N = 3.