Find the area between.x = 18 and .x = 23 under a normal distribution curve with μ = 20 and o = 4. Round your answer to four decimal places.

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### Problem Statement

**Objective:** Find the area between \( x = 18 \) and \( x = 23 \) under a normal distribution curve with \( \mu = 20 \) and \( \sigma = 4 \).

**Instructions:** Round your answer to four decimal places.

### Explanation and Solution

To find the area under a normal distribution curve between two points, you need to calculate the cumulative probabilities for each point and then determine the difference between these probabilities. 

1. **Standardize the values of \( x \):**
   Standardized values (z-scores) can be computed as:
   \[
   z = \frac{x - \mu}{\sigma}
   \]

   For \( x = 18 \):
   \[
   z_1 = \frac{18 - 20}{4} = \frac{-2}{4} = -0.5
   \]

   For \( x = 23 \):
   \[
   z_2 = \frac{23 - 20}{4} = \frac{3}{4} = 0.75
   \]

2. **Use the z-scores to find cumulative probabilities** from the standard normal distribution table or a computational tool:
   
   \[
   P(Z < -0.5) \approx 0.3085
   \]
   
   \[
   P(Z < 0.75) \approx 0.7734
   \]

3. **Calculate the area between these two points** by finding the difference between the cumulative probabilities:
   \[
   \text{Area} = P(Z < 0.75) - P(Z < -0.5) 
   \]

   \[
   \text{Area} = 0.7734 - 0.3085 = 0.4649
   \]

Therefore, the area between \( x = 18 \) and \( x = 23 \) under the specified normal distribution curve is approximately \( 0.4649 \).
Transcribed Image Text:### Problem Statement **Objective:** Find the area between \( x = 18 \) and \( x = 23 \) under a normal distribution curve with \( \mu = 20 \) and \( \sigma = 4 \). **Instructions:** Round your answer to four decimal places. ### Explanation and Solution To find the area under a normal distribution curve between two points, you need to calculate the cumulative probabilities for each point and then determine the difference between these probabilities. 1. **Standardize the values of \( x \):** Standardized values (z-scores) can be computed as: \[ z = \frac{x - \mu}{\sigma} \] For \( x = 18 \): \[ z_1 = \frac{18 - 20}{4} = \frac{-2}{4} = -0.5 \] For \( x = 23 \): \[ z_2 = \frac{23 - 20}{4} = \frac{3}{4} = 0.75 \] 2. **Use the z-scores to find cumulative probabilities** from the standard normal distribution table or a computational tool: \[ P(Z < -0.5) \approx 0.3085 \] \[ P(Z < 0.75) \approx 0.7734 \] 3. **Calculate the area between these two points** by finding the difference between the cumulative probabilities: \[ \text{Area} = P(Z < 0.75) - P(Z < -0.5) \] \[ \text{Area} = 0.7734 - 0.3085 = 0.4649 \] Therefore, the area between \( x = 18 \) and \( x = 23 \) under the specified normal distribution curve is approximately \( 0.4649 \).
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