Part 5: Assessing the Relationship Between the Variables Use the reference summary and graphs for the least-squares regression model for temperature. 28. What is the t* critical value for a 95% confidence interval of the true slope of the linear model for temperature using this sample size? How many degrees of freedom here? 29. Estimate the true slope of the linear model for temperature using a 95% confidence level. Make sure to interpret your estimate as a slope.