1. **State the problem:** A box contains 10 counters, red and green, with a ratio of red to green counters as 1:4. Shareen picks a counter at random, notes its color, replaces it, and then picks a second counter. We need to complete the tree diagram and find the probability that both counters are green. 2. **Find the number of red and green counters:** The ratio red:green = 1:4 means for every 1 red counter, there are 4 green counters. Total parts = 1 + 4 = 5. Number of red counters = $\frac{1}{5} \times 10 = 2$. Number of green counters = $\frac{4}{5} \times 10 = 8$. 3. **Calculate probabilities for the first pick:** Probability of red (first pick) = $\frac{2}{10} = 0.2$. Probability of green (first pick) = $\frac{8}{10} = 0.8$. 4. **Since the counter is replaced, probabilities for the second pick remain the same:** Probability of red (second pick) = $0.2$. Probability of green (second pick) = $0.8$. 5. **Complete the tree diagram probabilities:** - From first red: - Second red: $0.2$. - Second green: $0.8$. - From first green: - Second red: $0.2$. - Second green: $0.8$. 6. **Find the probability that both counters are green:** $$P(\text{green, then green}) = P(\text{green first}) \times P(\text{green second}) = 0.8 \times 0.8 = 0.64.$$