(c) Suppose the manager agrees to pay each employee a $50 bonus if they meet a certain goal. On a typical Saturday, the oil-change facility will perform 45 oil changes between 10 A.M. and 12 P.M. Treating this as a random sample, at what mean oil-change time would there be a 10% chance of being at or below? This will be the goal established by the manager. There would be a 10% chance of being at or below minutes. (Round to one decimal place as needed.)

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### Exploring Oil Change Time Distribution

The shape of the distribution for the time required to get an oil change at a 20-minute oil-change facility is skewed right. Records indicate a mean time of 21.8 minutes with a standard deviation of 4.2 minutes. Let's explore this through the following tasks:

#### View Distribution Tables
- [Standard normal distribution table (page 1)](URL)
- [Standard normal distribution table (page 2)](URL)

### Tasks

#### (a) Required Sample Size for Normal Model
To compute probabilities regarding the sample mean using a normal model, consider the following:

**Choose the appropriate statement:**
- **A.** The sample size needs to be greater than 30.
- **B.** The sample size needs to be less than 30.
- **C.** Any sample size could be used.
- **D.** The normal model cannot be used if the shape of the distribution is skewed right.

#### (b) Probability for Mean Time Less than 20 Minutes
Calculate the probability that a random sample of \( n = 45 \) oil changes results in a sample mean time less than 20 minutes.

- **Probability is approximately:** \( 0.0021 \)
- *(Round to four decimal places as needed.)*

#### (c) Manager's Goal for Employee Bonus
Suppose each employee can earn a $50 bonus for meeting a certain goal. For a typical Saturday, the facility performs 45 oil changes between 10 A.M. and 12 P.M. Using this as a random sample, determine the mean oil-change time for a 10% chance of being at or below.

- **Mean time for a 10% chance:** \( \_ \_ \_ \_ \_ \_ \) minutes
- *(Round to one decimal place as needed.)*
Transcribed Image Text:### Exploring Oil Change Time Distribution The shape of the distribution for the time required to get an oil change at a 20-minute oil-change facility is skewed right. Records indicate a mean time of 21.8 minutes with a standard deviation of 4.2 minutes. Let's explore this through the following tasks: #### View Distribution Tables - [Standard normal distribution table (page 1)](URL) - [Standard normal distribution table (page 2)](URL) ### Tasks #### (a) Required Sample Size for Normal Model To compute probabilities regarding the sample mean using a normal model, consider the following: **Choose the appropriate statement:** - **A.** The sample size needs to be greater than 30. - **B.** The sample size needs to be less than 30. - **C.** Any sample size could be used. - **D.** The normal model cannot be used if the shape of the distribution is skewed right. #### (b) Probability for Mean Time Less than 20 Minutes Calculate the probability that a random sample of \( n = 45 \) oil changes results in a sample mean time less than 20 minutes. - **Probability is approximately:** \( 0.0021 \) - *(Round to four decimal places as needed.)* #### (c) Manager's Goal for Employee Bonus Suppose each employee can earn a $50 bonus for meeting a certain goal. For a typical Saturday, the facility performs 45 oil changes between 10 A.M. and 12 P.M. Using this as a random sample, determine the mean oil-change time for a 10% chance of being at or below. - **Mean time for a 10% chance:** \( \_ \_ \_ \_ \_ \_ \) minutes - *(Round to one decimal place as needed.)*
**Standard Normal Distribution Table (Page 1 and Page 2)**

The standard normal distribution table is used to find the probability that a normally distributed random variable Z, with mean 0 and standard deviation 1, is less than or equal to a given value.

**Diagrams:**
Each page features a bell curve representing the standard normal distribution. The area under the curve to the left of a vertical line at a specified Z value represents the cumulative probability for that Z score.

**Table Layout:**
- The tables include Z scores in increments of 0.01.
- The leftmost column lists the integer and first decimal of Z values.
- The topmost row lists the second decimal point of Z values.
- The intersecting cells display the cumulative probability.

### Page 1

#### Z Scores and Probability Values:

- **Range: −3.4 to −0.1**
  
- Example:
  - For Z = −1.5 and 0.06: The probability is 0.0630.
  - For Z = −2.8 and 0.05: The probability is 0.0026.

### Page 2

#### Z Scores and Probability Values:

- **Range: 0.0 to 3.4**

- Example:
  - For Z = 1.2 and 0.03: The probability is 0.8907.
  - For Z = 2.5 and 0.08: The probability is 0.9924.

**Usage Note:**
When using the table, locate the Z score's integer and first decimal in the leftmost column, then find the second decimal in the topmost row. The cell where these intersect provides the cumulative probability.

These tables are essential for statistical analysis and hypothesis testing involving normal distributions.
Transcribed Image Text:**Standard Normal Distribution Table (Page 1 and Page 2)** The standard normal distribution table is used to find the probability that a normally distributed random variable Z, with mean 0 and standard deviation 1, is less than or equal to a given value. **Diagrams:** Each page features a bell curve representing the standard normal distribution. The area under the curve to the left of a vertical line at a specified Z value represents the cumulative probability for that Z score. **Table Layout:** - The tables include Z scores in increments of 0.01. - The leftmost column lists the integer and first decimal of Z values. - The topmost row lists the second decimal point of Z values. - The intersecting cells display the cumulative probability. ### Page 1 #### Z Scores and Probability Values: - **Range: −3.4 to −0.1** - Example: - For Z = −1.5 and 0.06: The probability is 0.0630. - For Z = −2.8 and 0.05: The probability is 0.0026. ### Page 2 #### Z Scores and Probability Values: - **Range: 0.0 to 3.4** - Example: - For Z = 1.2 and 0.03: The probability is 0.8907. - For Z = 2.5 and 0.08: The probability is 0.9924. **Usage Note:** When using the table, locate the Z score's integer and first decimal in the leftmost column, then find the second decimal in the topmost row. The cell where these intersect provides the cumulative probability. These tables are essential for statistical analysis and hypothesis testing involving normal distributions.
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