Let x denote the time it takes to run a road race. Suppose x is approximately normally distributed with a mean of 190 minutes and a standard deviation of 21 minutes. If one runner is selected at random, what is the probability that this runner will complete this roa race in less than 177 minutes?

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### Probability and Statistics: Normal Distribution

**Problem Statement:**

Let \( x \) denote the time it takes to run a road race. Suppose \( x \) is approximately normally distributed with a mean of 190 minutes and a standard deviation of 21 minutes. If one runner is selected at random, what is the probability that this runner will complete this road race in less than 177 minutes?

**Solution Steps:**

1. **Identify the given parameters:**
   - Mean (\( \mu \)): 190 minutes
   - Standard deviation (\( \sigma \)): 21 minutes
   - Target time (\( X = 177 \)) minutes

2. **Standardize the target time using the Z-score formula:**
   \[
   Z = \frac{X - \mu}{\sigma}
   \]
   Substitute the given values:
   \[
   Z = \frac{177 - 190}{21} = \frac{-13}{21} \approx -0.6190
   \]

3. **Find the corresponding probability:**
   Using standard normal distribution tables, or a calculator, find the probability associated with a Z-score of -0.6190.

**Expected Answer Format:**

Round your answer to four decimal places. 

\[
\boxed{}
\]

**Additional Information:**

- The blue icon with an "i" in it typically denotes an information or help button that can provide guidance or clarification when you hover over or click on it.
Transcribed Image Text:### Probability and Statistics: Normal Distribution **Problem Statement:** Let \( x \) denote the time it takes to run a road race. Suppose \( x \) is approximately normally distributed with a mean of 190 minutes and a standard deviation of 21 minutes. If one runner is selected at random, what is the probability that this runner will complete this road race in less than 177 minutes? **Solution Steps:** 1. **Identify the given parameters:** - Mean (\( \mu \)): 190 minutes - Standard deviation (\( \sigma \)): 21 minutes - Target time (\( X = 177 \)) minutes 2. **Standardize the target time using the Z-score formula:** \[ Z = \frac{X - \mu}{\sigma} \] Substitute the given values: \[ Z = \frac{177 - 190}{21} = \frac{-13}{21} \approx -0.6190 \] 3. **Find the corresponding probability:** Using standard normal distribution tables, or a calculator, find the probability associated with a Z-score of -0.6190. **Expected Answer Format:** Round your answer to four decimal places. \[ \boxed{} \] **Additional Information:** - The blue icon with an "i" in it typically denotes an information or help button that can provide guidance or clarification when you hover over or click on it.
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