Consider the population of commuting time to school for all John Jay College students during Spring 2022. The commuting times have a mean of 95 minutes and a standard deviation of 22 minutes. One student from STA 250-99 class had a commuting time of 2 hours and 15 minutes. What is the z score for this commuting time? (Give your answer correct to two decimal places.)

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**Understanding Z-Scores with Commuting Times**

Consider the population of commuting time to school for all John Jay College students during Spring 2022. The commuting times have a mean of 95 minutes and a standard deviation of 22 minutes. One student from STA 250-99 class had a commuting time of 2 hours and 15 minutes. What is the z score for this commuting time? (Give your answer correct to two decimal places.)

---

### Analysis and Explanation:

#### Definitions:
1. **Mean (μ):** The average value of all the commuting times, which is 95 minutes.
2. **Standard Deviation (σ):** A measure of how spread out the numbers are, which is 22 minutes.
3. **Z-Score:** The number of standard deviations a data point is from the mean.

#### Calculation Steps:
1. **Convert the commuting time to minutes**:
   - 2 hours and 15 minutes = 2 * 60 + 15 = 120 + 15 = 135 minutes.

2. **Apply the Z-Score formula**:
   \[
   Z = \frac{(X - \mu)}{\sigma}
   \]
   Where:
   - \( X \) = observed value (135 minutes)
   - \( \mu \) = mean (95 minutes)
   - \( \sigma \) = standard deviation (22 minutes)

3. **Substitute the values**:
   \[
   Z = \frac{(135 - 95)}{22}
   \]

4. **Calculate the Z-Score**:
   \[
   Z = \frac{40}{22} \approx 1.82
   \]

#### Conclusion:
The z score for the student's commuting time is approximately 1.82. This means the student's commuting time is 1.82 standard deviations above the mean commuting time.

---

**Note:** Z-Scores allow us to understand how a particular value compares to the overall distribution of the data. In this case, the student's commuting time is significantly above average.
Transcribed Image Text:**Understanding Z-Scores with Commuting Times** Consider the population of commuting time to school for all John Jay College students during Spring 2022. The commuting times have a mean of 95 minutes and a standard deviation of 22 minutes. One student from STA 250-99 class had a commuting time of 2 hours and 15 minutes. What is the z score for this commuting time? (Give your answer correct to two decimal places.) --- ### Analysis and Explanation: #### Definitions: 1. **Mean (μ):** The average value of all the commuting times, which is 95 minutes. 2. **Standard Deviation (σ):** A measure of how spread out the numbers are, which is 22 minutes. 3. **Z-Score:** The number of standard deviations a data point is from the mean. #### Calculation Steps: 1. **Convert the commuting time to minutes**: - 2 hours and 15 minutes = 2 * 60 + 15 = 120 + 15 = 135 minutes. 2. **Apply the Z-Score formula**: \[ Z = \frac{(X - \mu)}{\sigma} \] Where: - \( X \) = observed value (135 minutes) - \( \mu \) = mean (95 minutes) - \( \sigma \) = standard deviation (22 minutes) 3. **Substitute the values**: \[ Z = \frac{(135 - 95)}{22} \] 4. **Calculate the Z-Score**: \[ Z = \frac{40}{22} \approx 1.82 \] #### Conclusion: The z score for the student's commuting time is approximately 1.82. This means the student's commuting time is 1.82 standard deviations above the mean commuting time. --- **Note:** Z-Scores allow us to understand how a particular value compares to the overall distribution of the data. In this case, the student's commuting time is significantly above average.
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