Two coins are tossed simultaneously $500$ times,and we get:
Two heads : $105$ times
One head : $275$ times
No head : $120$ times
Find the probability of occurrence of each of these events.

(N/A) Let us denote the events of getting two heads,one head,and no head by $E_1, E_2,$ and $E_3$ respectively.
The total number of trials is $500$.
For $E_1$ (two heads): $P(E_1) = \frac{105}{500} = 0.21$
For $E_2$ (one head): $P(E_2) = \frac{275}{500} = 0.55$
For $E_3$ (no head): $P(E_3) = \frac{120}{500} = 0.24$
Observe that $P(E_1) + P(E_2) + P(E_3) = 0.21 + 0.55 + 0.24 = 1.0$. These events cover all possible outcomes of the trial.