We know that,
In throwing a dice, total possible outcomes $$= {1, 2, 3, 4, 5, 6}$$
So, $$n(S) = 6$$
On a dice, numbers greater than or equal to $$4 = {4, 5, 6}$$
So,$$ n(E) = 3$$
Hence, probability of getting a number greater than or equal to $$4 = n(E)/ n(S) = 3/6 = 1/2$$