3. It is reported that 85% of all freshman entering high school graduate on time with their class. A random sample of 145 freshmen are selected. a. Find the mean . 85± 145 0,59 0159 = 145 f = 24121046x c. Find the probability that less than 80% of freshmen in the sample graduated. b. Find the standard deviation op.

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### Transcription for Educational Website

#### Statistical Analysis of Freshman Graduation Rates

**Problem Statement:**
3. It is reported that 85% of all freshmen entering high school graduate on time with their class. A random sample of 145 freshmen is selected.

**Tasks:**

a. **Find the Mean, \( \mu_p \):**

   - The mean graduation rate is given as 85%, which is represented as \( f = 0.85 \).
   - Sample size (\( n \)) = 145.

b. **Find the Standard Deviation, \( \sigma_p \):**

   - Calculate the standard deviation using the formula for a sample proportion: 
     \[
     \sigma_p = \sqrt{\frac{f(1 - f)}{n}}
     \]
   - Substitution:
     \[
     \sigma_p = \sqrt{\frac{0.85 \times 0.15}{145}} \approx 0.059
     \]

c. **Find the Probability that Less than 80% of Freshmen in the Sample Graduated:**

   - Use the z-score formula to find the probability:
     \[
     z = \frac{p - \mu_p}{\sigma_p}
     \]
     where \( p = 0.80 \).
   - Calculation of z-score:
     \[
     z = \frac{0.80 - 0.85}{0.059} \approx -1.81
     \]

**Note:**
- The text includes some handwritten calculations which confirm the steps mentioned.
- There are no graphs or diagrams present in the image.
Transcribed Image Text:### Transcription for Educational Website #### Statistical Analysis of Freshman Graduation Rates **Problem Statement:** 3. It is reported that 85% of all freshmen entering high school graduate on time with their class. A random sample of 145 freshmen is selected. **Tasks:** a. **Find the Mean, \( \mu_p \):** - The mean graduation rate is given as 85%, which is represented as \( f = 0.85 \). - Sample size (\( n \)) = 145. b. **Find the Standard Deviation, \( \sigma_p \):** - Calculate the standard deviation using the formula for a sample proportion: \[ \sigma_p = \sqrt{\frac{f(1 - f)}{n}} \] - Substitution: \[ \sigma_p = \sqrt{\frac{0.85 \times 0.15}{145}} \approx 0.059 \] c. **Find the Probability that Less than 80% of Freshmen in the Sample Graduated:** - Use the z-score formula to find the probability: \[ z = \frac{p - \mu_p}{\sigma_p} \] where \( p = 0.80 \). - Calculation of z-score: \[ z = \frac{0.80 - 0.85}{0.059} \approx -1.81 \] **Note:** - The text includes some handwritten calculations which confirm the steps mentioned. - There are no graphs or diagrams present in the image.
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