To calculate the probability that Lana randomly chooses a blue marble, replaces it, and then chooses a purple marble, follow these steps:
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Determine the total number of marbles.
Lana has a total of:- 2 black
- 5 blue
- 3 red
- 3 green
- 2 purple
So, the total number of marbles = \( 2 + 5 + 3 + 3 + 2 = 15 \).
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Calculate the probability of choosing a blue marble.
The probability of choosing a blue marble: \[ P(\text{blue}) = \frac{\text{Number of blue marbles}}{\text{Total number of marbles}} = \frac{5}{15} = \frac{1}{3}. \] -
Calculate the probability of choosing a purple marble.
The probability of choosing a purple marble: \[ P(\text{purple}) = \frac{\text{Number of purple marbles}}{\text{Total number of marbles}} = \frac{2}{15}. \] -
Combine the probabilities.
Since Lana replaces the blue marble before choosing the next one, the two events are independent. Therefore, the combined probability is: \[ P(\text{blue and then purple}) = P(\text{blue}) \times P(\text{purple}) = \frac{1}{3} \times \frac{2}{15} = \frac{2}{45}. \]
Thus, the probability that she randomly chooses a blue marble, replaces it, and then chooses a purple marble is \( \frac{2}{45} \).
The final answer is: \[ \frac{2}{45}. \]