1. **Problem statement:**
Calculate the probabilities of drawing sequences of red (R) and blue (B) balls from a set where the probability of red is $0.6$ and blue is $0.4$, following the given tree diagram.
2. **Given:**
- $P(\text{red}) = 0.6$
- $P(\text{blue}) = 0.4$
3. **Understanding the tree diagram:**
- First draw: red with probability $0.6$, blue with probability $0.4$.
- Second draw depends on the first:
- If first is red, second is red with $0.6$, blue with $0.4$.
- If first is blue, second is red with $0.6$, blue with $0.4$.
4. **Calculate probabilities for each two-draw sequence:**
- $P(RR) = P(R) \times P(R|R) = 0.6 \times 0.6 = 0.36$
- $P(RB) = P(R) \times P(B|R) = 0.6 \times 0.4 = 0.24$
- $P(BR) = P(B) \times P(R|B) = 0.4 \times 0.6 = 0.24$
- $P(BB) = P(B) \times P(B|B) = 0.4 \times 0.4 = 0.16$
5. **Check total probability:**
$$0.36 + 0.24 + 0.24 + 0.16 = 1.0$$
6. **Interpretation:**
- The probabilities of all possible two-draw sequences sum to 1, confirming the correctness.
**Final answer:**
- $P(RR) = 0.36$
- $P(RB) = 0.24$
- $P(BR) = 0.24$
- $P(BB) = 0.16$
Probability Tree 801376
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