Consider the following results for independent random samples taken from two populations. Sample 1 n1 = 20 Sample 2 n2 = 30 X 2 = 20.7 X 1 = 22.3 $1 = 2.5 $ 2 = 4.4 a. What is the point estimate of the difference between the two population means (to 1 decimal)? b. What is the degrees of freedom for the t distribution (round down your answer to nearest whole number)? c. At 95% confidence, what is the margin of error (to 1 decimal)? d. What is the 95% confidence interval for the difference between the two population means (to 1 decimal)? If your answer is negative value, entre minus (-) sign. Use z-table.