I’m not sure but i think 66 hours because both pumps must fill half of the pool which would split the timing for each which would make pump 1 take 36 hours to fill half and pump two take 30 hours to fill the rest. when you add these hours it equals 66. i hope i helped :)
36;
the square root and the square cancel out, or you can work it out and say
((36)^1/2)^2 = (6)^2= 36
C because there are 60 seconds in a minute so if you multiply 600 x 60 you get 36000
