Answer:
0.12 = 12% probability of first selecting a PRIME number, replacing it, then selecting a number less than or equal to 3
Step-by-step explanation:
A probability is the number of desired outcomes divided by the number of total outcomes.
Probability of independent events:
Suppose we have two events, A and B, that are independent. The probability of both happening is given by:
![P(A \cap B) = P(A) \times P(B)](https://tex.z-dn.net/?f=P%28A%20%5Ccap%20B%29%20%3D%20P%28A%29%20%5Ctimes%20P%28B%29)
In this question:
Event A: Selecting a prime number.
Event B: Selecting a number less than or equal to 3
Probability of selecting a prime number:
Between 1 and 10, we have 4 prime numbers(2,3, 5 and 7), out of 10. So
![P(A) = \frac{4}{10}](https://tex.z-dn.net/?f=P%28A%29%20%3D%20%5Cfrac%7B4%7D%7B10%7D)
Probability of selecting a number less than or equal to 3:
Three numbers(1,2,3) out of 10. So
![P(B) = \frac{3}{10}](https://tex.z-dn.net/?f=P%28B%29%20%3D%20%5Cfrac%7B3%7D%7B10%7D)
Probability of both:
![P(A \cap B) = P(A) \times P(B) = \frac{4}{10} \times \frac{3}{10} = \frac{12}{100} = 0.12](https://tex.z-dn.net/?f=P%28A%20%5Ccap%20B%29%20%3D%20P%28A%29%20%5Ctimes%20P%28B%29%20%3D%20%5Cfrac%7B4%7D%7B10%7D%20%5Ctimes%20%5Cfrac%7B3%7D%7B10%7D%20%3D%20%5Cfrac%7B12%7D%7B100%7D%20%3D%200.12)
0.12 = 12% probability of first selecting a PRIME number, replacing it, then selecting a number less than or equal to 3