Question

If E1, E2, E3, ....., En are n elemantary events associated to a random experiment, then P(E1) + P(E2) + P(E3) + ........... + P(En) = ___

• A. 0
• B. 1
• C. Depends on situation
• D. 2

Answer 1

The correct option is B 1

A sum of probabilities of all events in an experiment equals 1. For example, if we toss a coin there are two possibilities either head turns up or tail turns up. Probability of head is $\frac{1}{2}$ and probability of tail is $\frac{1}{2}$. Sum of all probabilities = $\frac{1}{2}+\frac{1}{2}=1$.