In order to determine the probability that from 60 lambs born on BaaBaa, 33 of them are males, you first consider that both malen and females are equalliy probable. This means that the probability at every birth to get a male or a female is 1/2 = 0.5.
Now, you calculate the quotient between the number of male about you want to know the probability (33), and the total number of lambs born (60):
33/60 = 0.55
next, you multiply the last result by the probability of obtaining one male or one female (0.5)
(0.55) x (0.5) = 0.275
next, multiply the previoues result by 100:
0.275 x 100 = 27.5
Hence, the probability is of 27.5%