Questions: Suppose L and M are not mutually exclusive events with P(L)=0.45, P(M)=0.55, P(L and M)=0.2. Find P(L or M).
Transcript text: Suppose $L$ and $M$ are not mutually exclusive events with $P(L)=0.45, P(M)=0.55, P(L$ and $M)=0.2 \quad$ Find $P(L$ or $M)$.
Solution
Solution Steps
To find the probability of either event \( L \) or event \( M \) occurring, we use the formula for the probability of the union of two events:
\[ P(L \text{ or } M) = P(L) + P(M) - P(L \text{ and } M) \]
This formula accounts for the overlap between the two events, which is subtracted to avoid double-counting.
Step 1: Given Probabilities
We are given the following probabilities:
\( P(L) = 0.45 \)
\( P(M) = 0.55 \)
\( P(L \text{ and } M) = 0.2 \)
Step 2: Apply the Union Formula
To find \( P(L \text{ or } M) \), we use the formula for the probability of the union of two events:
\[
P(L \text{ or } M) = P(L) + P(M) - P(L \text{ and } M)
\]
Step 3: Substitute Values
Substituting the given values into the formula:
\[
P(L \text{ or } M) = 0.45 + 0.55 - 0.2
\]
Step 4: Perform the Calculation
Calculating the expression:
\[
P(L \text{ or } M) = 1.0 - 0.2 = 0.8
\]
Final Answer
Thus, the probability of either event \( L \) or event \( M \) occurring is
\[
\boxed{P(L \text{ or } M) = 0.8}
\]