To find the probability of two events occurring, you must multiply their individual probabilities.
Thus,
the probability of getting heads when flipping a coin is :
favorable outcomes/total outcomes = 1/2
The probability of getting a number greater than or equal to 4 when rolling a single die is:
favorable outcomes/total outcomes = 3/6 =1/2
Now, we have to multiply the two probabilities.
1/2 * 1/2 = 1/4
1/4 or 25% is the probability of the above events occurring.