help me solve

1) Given a sample with r = 0.433, n = 20, at alpha = 0.05, is r significant and can the line be used for prediction?

2)Given the equation of a regression line is y-hat = 3.5x - 5.4, what is the best predicted value for y given x = -1.2? Assume that the variables x and y have a significant correlation

3)Given a sample with r = 0.833, n = 8, at alpha = 0.05, is r significant and can the line be used for prediction?