Question

There are three candidates A, B and C contesting in an election. The winning probability of A is 40% and winning probability of B is 30%. Find the probability that A or B will win the election.

• A. 1
• B. 0.4
• C. 0.3
• D. 0.7

Answer 1

The correct option is D 0.7

Given that the winning probability of A = 40%
$\Rightarrow$P(A wins) = 0.4
and, the winning probability of B = 30%
$\Rightarrow$P(B wins) = 0.3
For the winning probability of A or B, we have
$P(A\cup B)=P\left(A\right)+P\left(B\right)-P(A\cap B)$
Since A and B cannot win together
So, $P(A\cap B)=0$
$\mathrm{Now,}$$P(A\cup B)=0.4+0.3-0$
$P(A\cup B)=0.7$
Therefore, probability of winning A or B is 0.7.