Suppose that [tex]$A$[/tex] and [tex]$B$[/tex] are independent events such that [tex]$P(A)=0.60$[/tex] and [tex]$P(\bar{B})=0.20$[/tex]. Find [tex]$P(A \cap B)$[/tex] and [tex]$P(A \cup B)$[/tex].

(a) [tex]$P(A \cap B)=$[/tex] [tex]$\square$[/tex]

(b) [tex]$P(A \cup B)=$[/tex] [tex]$\square$[/tex]



Answer :

Certainly! Let's work through this problem step by step to find [tex]\( P(A \cap B) \)[/tex] and [tex]\( P(A \cup B) \)[/tex] given that [tex]\( P(A) = 0.60 \)[/tex] and [tex]\( P(\bar{B}) = 0.20 \)[/tex].

### Step 1: Determine [tex]\( P(B) \)[/tex]
First, we know that [tex]\( P(\bar{B}) \)[/tex] is the probability that event [tex]\( B \)[/tex] does not occur. The complement rule states that the probability of [tex]\( B \)[/tex] occurring, [tex]\( P(B) \)[/tex], is given by:

[tex]\[ P(B) = 1 - P(\bar{B}) \][/tex]

Given [tex]\( P(\bar{B}) = 0.20 \)[/tex]:

[tex]\[ P(B) = 1 - 0.20 = 0.80 \][/tex]

### Step 2: Calculate [tex]\( P(A \cap B) \)[/tex]
Since events [tex]\( A \)[/tex] and [tex]\( B \)[/tex] are independent, the probability of both events occurring, [tex]\( P(A \cap B) \)[/tex], is the product of their individual probabilities:

[tex]\[ P(A \cap B) = P(A) \times P(B) \][/tex]

Given [tex]\( P(A) = 0.60 \)[/tex] and [tex]\( P(B) = 0.80 \)[/tex]:

[tex]\[ P(A \cap B) = 0.60 \times 0.80 = 0.48 \][/tex]

Hence, [tex]\( P(A \cap B) = 0.48 \)[/tex].

### Step 3: Calculate [tex]\( P(A \cup B) \)[/tex]
The probability of either event [tex]\( A \)[/tex] or [tex]\( B \)[/tex] occurring, [tex]\( P(A \cup B) \)[/tex], for independent events, is given by:

[tex]\[ P(A \cup B) = P(A) + P(B) - P(A \cap B) \][/tex]

Using the values we have:

[tex]\[ P(A \cup B) = 0.60 + 0.80 - 0.48 \][/tex]

Simplifying:

[tex]\[ P(A \cup B) = 1.40 - 0.48 = 0.92 \][/tex]

Hence, [tex]\( P(A \cup B) = 0.92 \)[/tex].

### Summary
(a) [tex]\( P(A \cap B) = 0.48 \)[/tex]

(b) [tex]\( P(A \cup B) = 0.92 \)[/tex]

These are the probabilities for the given events [tex]\( A \)[/tex] and [tex]\( B \)[/tex].