The inside diameter of a randomly selected piston ring is a random variable with mean value 9 cm and standard deviation 0.07 cm. Suppose the distribution of the diameter is normal. (Round your answers to four decimal places.) Calculate P(8.99 < X < 9.01) when n = 16.

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
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ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section10.4: Distributions Of Data
Problem 22PFA
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### Problem Statement: Understanding the Distribution of Piston Ring Diameters

**Description:**
The inside diameter of a randomly selected piston ring is a random variable with a mean value of 9 cm and a standard deviation of 0.07 cm. Suppose the distribution of the diameter is normal. The goal is to calculate the probability for a specific range of mean diameters when the sample size \( n = 16 \).

**Problem:**
Calculate \( P(8.99 \leq \bar{X} \leq 9.01) \) when \( n = 16 \).

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

**Steps to Solve:**
1. Understand the problem is focused on a normally distributed variable, specifically the inside diameter of a piston ring.
2. Identify given parameters:
    - Mean (\(\mu\)) = 9 cm
    - Standard Deviation (\(\sigma\)) = 0.07 cm
    - Sample size (\(n\)) = 16
3. Use these parameters to calculate the distribution of the sample mean \(\bar{X}\).
4. The standard error (SE) of the mean is calculated as:
   \[
   SE = \frac{\sigma}{\sqrt{n}} = \frac{0.07}{\sqrt{16}} = \frac{0.07}{4} = 0.0175
   \]
5. Convert the problem into the standard normal distribution (Z-distribution) using the Z-score formula:
   \[
   Z = \frac{\bar{X} - \mu}{SE}
   \]
6. Calculate the Z-scores for the boundaries:
   \[
   Z_1 = \frac{8.99 - 9}{0.0175}, \quad Z_2 = \frac{9.01 - 9}{0.0175}
   \]
7. Use the Z-scores to find the probabilities from the standard normal distribution tables or a calculator to get the final probability.

This problem aims to test the understanding of normal distribution, standard error, and Z-scores, which are fundamental concepts in statistics.
Transcribed Image Text:### Problem Statement: Understanding the Distribution of Piston Ring Diameters **Description:** The inside diameter of a randomly selected piston ring is a random variable with a mean value of 9 cm and a standard deviation of 0.07 cm. Suppose the distribution of the diameter is normal. The goal is to calculate the probability for a specific range of mean diameters when the sample size \( n = 16 \). **Problem:** Calculate \( P(8.99 \leq \bar{X} \leq 9.01) \) when \( n = 16 \). **Instructions:** Round your answers to four decimal places. **Steps to Solve:** 1. Understand the problem is focused on a normally distributed variable, specifically the inside diameter of a piston ring. 2. Identify given parameters: - Mean (\(\mu\)) = 9 cm - Standard Deviation (\(\sigma\)) = 0.07 cm - Sample size (\(n\)) = 16 3. Use these parameters to calculate the distribution of the sample mean \(\bar{X}\). 4. The standard error (SE) of the mean is calculated as: \[ SE = \frac{\sigma}{\sqrt{n}} = \frac{0.07}{\sqrt{16}} = \frac{0.07}{4} = 0.0175 \] 5. Convert the problem into the standard normal distribution (Z-distribution) using the Z-score formula: \[ Z = \frac{\bar{X} - \mu}{SE} \] 6. Calculate the Z-scores for the boundaries: \[ Z_1 = \frac{8.99 - 9}{0.0175}, \quad Z_2 = \frac{9.01 - 9}{0.0175} \] 7. Use the Z-scores to find the probabilities from the standard normal distribution tables or a calculator to get the final probability. This problem aims to test the understanding of normal distribution, standard error, and Z-scores, which are fundamental concepts in statistics.
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