Question 7 The following regression results relate to a study of the salaries of public-school teachers in a mid-western city (the sample size was 450 teachers): Standard Variable Coefficient Error Constant 20,720 6,820 EXP 805 258 R-squared = 0.684; Standard error of the estimate = 2,000. EXP is the experience of teachers in years of full-time teaching. What percentage of the variation in salary is explained by this model? 3 pts Question 6 The following regression results relate to a study of the salaries of public-school teachers in a mid-western city (the sample size was 450 teachers): Standard Variable Coefficient Error Constant 20,720 6,820 EXP 805 258 R-squared 0.684; Standard error of the estimate = 2,000. EXP is the experience of teachers in years of full-time teaching. 3 pts What is the higher limit of the approximate 95 percent confidence interval for your 20 years of experience point estimate? Question 4 The following regression results relate to a study of the salaries of public-school teachers in a mid-western city (the sample size was 450 teachers): Standard Variable Coefficient Error Constant 20,720 6,820 EXP 805 258 = R-squared 0.684; Standard error of the estimate = 2,000. EXP is the experience of teachers in years of full-time teaching. 3 pts What is the lower limit of the approximate 95 percent confidence interval for your 20 years of experience point estimate?