The prices of used books at a large college bookstore are normally distributed. If a sample of 23 used books from this store has a mean price of $27.50 with a standard deviation of $6.75, use Table 10.1 to calculate the following for a 95% confidence level about the population mean. a. Degrees of freedom b. The critical value of t c. The margin of error d. The confidence interval for a 95% confidence level

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The prices of used books at a large college bookstore are normally distributed. If a sample of 23 used books from this store has a mean price of $27.50 with a standard deviation of $6.75, use Table 10.1 to calculate the following for a 95% confidence level about the population mean.

a. Degrees of freedom

b. The critical value of t

c. The margin of error

d. The confidence interval for a 95% confidence level

 

### Table 10.1: Critical t Values

#### Description
This table provides t-critical values for different degrees of freedom (df) at a significance level of 0.05 for both one-tailed and two-tailed tests. 

#### How to Use the Table:
- **Degrees of Freedom (df)**: This is typically calculated as the sample size (n) minus 1 (df = n - 1).
- **Two-Tailed Test**: If you are conducting a two-tailed test with a 0.05 significance level, locate the critical value under the column labeled "0.05 area in two tails".
- **One-Tailed Test**: If you are conducting a one-tailed test with a 0.05 significance level, locate the critical value under the column labeled "0.05 area in one tail".

#### Table:

| Degrees of Freedom (n – 1) | 0.05 area in two tails | 0.05 area in one tail | Degrees of Freedom (n – 1) | 0.05 area in two tails | 0.05 area in one tail |
|---|---|---|---|---|---|
| 1  | 12.706 | 6.314 | 28 | 2.048 | 1.701 |
| 2  | 4.303  | 2.920  | 29 | 2.045 | 1.699 |
| 3  | 3.182  | 2.353  | 30 | 2.042 | 1.697 |
| 4  | 2.776  | 2.132  | 31 | 2.040 | 1.696 |
| 5  | 2.571  | 2.015  | 32 | 2.037 | 1.694 |
| 6  | 2.447  | 1.943  | 33 | 2.035 | 1.692 |
| 7  | 2.365  | 1.895  | 34 | 2.032 | 1.691 |
| 8  | 2.306  | 1.860  | 35 | 2.030 | 1.690 |
| 9  | 2.262  | 1.833
Transcribed Image Text:### Table 10.1: Critical t Values #### Description This table provides t-critical values for different degrees of freedom (df) at a significance level of 0.05 for both one-tailed and two-tailed tests. #### How to Use the Table: - **Degrees of Freedom (df)**: This is typically calculated as the sample size (n) minus 1 (df = n - 1). - **Two-Tailed Test**: If you are conducting a two-tailed test with a 0.05 significance level, locate the critical value under the column labeled "0.05 area in two tails". - **One-Tailed Test**: If you are conducting a one-tailed test with a 0.05 significance level, locate the critical value under the column labeled "0.05 area in one tail". #### Table: | Degrees of Freedom (n – 1) | 0.05 area in two tails | 0.05 area in one tail | Degrees of Freedom (n – 1) | 0.05 area in two tails | 0.05 area in one tail | |---|---|---|---|---|---| | 1 | 12.706 | 6.314 | 28 | 2.048 | 1.701 | | 2 | 4.303 | 2.920 | 29 | 2.045 | 1.699 | | 3 | 3.182 | 2.353 | 30 | 2.042 | 1.697 | | 4 | 2.776 | 2.132 | 31 | 2.040 | 1.696 | | 5 | 2.571 | 2.015 | 32 | 2.037 | 1.694 | | 6 | 2.447 | 1.943 | 33 | 2.035 | 1.692 | | 7 | 2.365 | 1.895 | 34 | 2.032 | 1.691 | | 8 | 2.306 | 1.860 | 35 | 2.030 | 1.690 | | 9 | 2.262 | 1.833
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