Song Length Probabilities
1. **Define the continuous random variable:**
Let $X$ be the length of a Taylor Swift song in seconds. Since song lengths vary continuously, $X$ is a continuous random variable.
2. **Find $P(X \leq 160)$:**
a) Probability statement: $P(X \leq 160)$.
b) This corresponds to the area under the normal distribution curve to the left of 160 seconds.
c) To find this probability, we calculate the z-score:
$$z = \frac{160 - \mu}{\sigma}$$
Assuming the mean $\mu = 200$ seconds and standard deviation $\sigma = 30$ seconds (typical values for song lengths),
$$z = \frac{160 - 200}{30} = \frac{-40}{30} = -1.33$$
Using the z-score table, $P(Z \leq -1.33) \approx 0.0918$.
3. **Find $P(180 \leq X \leq 220)$:**
a) Probability statement: $P(180 \leq X \leq 220)$.
b) This is the area under the curve between 180 and 220 seconds.
c) Calculate z-scores:
$$z_1 = \frac{180 - 200}{30} = -0.67$$
$$z_2 = \frac{220 - 200}{30} = 0.67$$
From the z-table:
$P(Z \leq 0.67) \approx 0.7486$
$P(Z \leq -0.67) \approx 0.2514$
So,
$$P(180 \leq X \leq 220) = 0.7486 - 0.2514 = 0.4972$$
4. **Find $P(X > 226)$ where 226 seconds = 3 minutes 46 seconds:**
a) Probability statement: $P(X > 226)$.
b) This is the area under the curve to the right of 226 seconds.
c) Calculate z-score:
$$z = \frac{226 - 200}{30} = \frac{26}{30} = 0.87$$
From the z-table:
$P(Z \leq 0.87) \approx 0.8078$
Therefore,
$$P(X > 226) = 1 - 0.8078 = 0.1922$$
**Final answers:**
- $P(X \leq 160) \approx 0.0918$
- $P(180 \leq X \leq 220) \approx 0.4972$
- $P(X > 226) \approx 0.1922$