1. **Problem 2:** Find the probability that a randomly drawn piece of paper from numbers 1 through 30 has a prime number.
2. **Step 1:** Identify all prime numbers between 1 and 30.
Prime numbers are numbers greater than 1 that have no divisors other than 1 and themselves.
The prime numbers between 1 and 30 are: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29.
There are 10 prime numbers.
3. **Step 2:** Calculate the probability.
Probability = \frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}} = \frac{10}{30}.
4. **Step 3:** Simplify the fraction.
$$\frac{\cancel{10}}{\cancel{30}} = \frac{1}{3}$$
So the probability is $\frac{1}{3}$, which is not exactly one of the options given, but closest to $\frac{10}{30}$ (option J).
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5. **Problem 3:** Given $\sin \alpha = \frac{5}{13}$ and $\tan \alpha = \frac{5}{12}$, find $\cos \alpha$.
6. **Step 1:** Recall the definitions.
$\sin \alpha = \frac{\text{opposite}}{\text{hypotenuse}}$, $\cos \alpha = \frac{\text{adjacent}}{\text{hypotenuse}}$, and $\tan \alpha = \frac{\text{opposite}}{\text{adjacent}}$.
7. **Step 2:** From $\sin \alpha = \frac{5}{13}$, opposite side = 5, hypotenuse = 13.
From $\tan \alpha = \frac{5}{12}$, opposite side = 5, adjacent side = 12.
8. **Step 3:** Calculate $\cos \alpha$.
$$\cos \alpha = \frac{\text{adjacent}}{\text{hypotenuse}} = \frac{12}{13}$$
**Final answers:**
- Probability of prime number = $\frac{10}{30}$ (option J).
- $\cos \alpha = \frac{12}{13}$.
Probability Cosine 8B815E
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