If the lights at both crossings showed the same colour when Eve arrived, what is the probability that they both showed red?
Give your answer as a fraction in its simplest form.
First crossing
Second crossing

Answer

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Answer

Find the probability that both lights showed red when Eve arrived: \(\frac{1}{3} \times \frac{1}{3} = \boxed{\frac{1}{9}}\)

Steps

Step 1 ：Assume the lights can show three colors: red, green, and yellow with equal probability, i.e., \(\frac{1}{3}\) for each color.

Step 2 ：Find the probability that both lights showed red when Eve arrived: \(\frac{1}{3} \times \frac{1}{3} = \boxed{\frac{1}{9}}\)