Use the following to answer the questions below:
Data were collected on GPA and number of Facebook friends for students in a small statistics class. Some summary statistics, partial output from the regression analysis, and a scatterplot of the data (with regression line) are provided. Assume that students in this class are typical of all students at the university.
Use three decimal places when reporting the results from any calculations, unless otherwise specified.
| Variable | Mean | StDev | Minimum | Maximum |
| GPA | 3.2067 | 0.4118 | 2.4000 | 3.9500 |
| FacebookFriends | 677.9 | 307.2 | 185.0 | 1500.0 |
The regression equation is GPA = 3.830 - 0.000919 FacebookFriends
| Source | DF | SS | MS | F | P |
| Regression | 1 | 2.31193 | 2.31193 | 24.85 | 0.000 |
| Error | 28 | 2.60534 | 0.09305 | | |
| Total | 29 | 4.91727 | | | |
Use the following output to identify and interpret a 95% interval for the GPA of a single student with 500 Facebook friends.
Predicted Values for New Observations
| FacebookFriends | Fit | SE Fit | 95% CI | 95% PI |
| 500 | 3.3702 | 0.0646 | (3.2378, 3.5026) | (2.7315, 4.0089) |
▸ CI: (3.2378, 3.5036)
We are 95% sure that the mean GPA for all students with 500 Facebook friends is between 3.2378 and 3.5036.
▸ PI: (2.7315, 4.0089)
We are 95% sure that the GPA of a student with 500 Facebook friends is between 2.7315 and 4.0089.
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