Answer:
Null hypothesis:
Alternative hypothesis:
The statistic to check the hypothesis is given by:
And is distributed with n-2 degrees of freedom
And the statistic to check the significance of a coeffcient in a regression is given by:

For this case is importantto remember that t1 and p value for test of slope coefficient is the same test statistic and p value for the correlation test so then the answer would be:
Always
Step-by-step explanation:
In order to test the hypothesis if the correlation coefficient it's significant we have the following hypothesis:
Null hypothesis:
Alternative hypothesis:
The statistic to check the hypothesis is given by:
And is distributed with n-2 degrees of freedom
And the statistic to check the significance of a coeffcient in a regression is given by:

For this case is importantto remember that t1 and p value for test of slope coefficient is the same test statistic and p value for the correlation test so then the answer would be:
Always
Slope = (y2-y1)/(x2-x1)
(3+1)/(2-0) = 4/2 = 2
The slope is 2
Answer:
-18
Step-by-step explanation:
18/3=6
6/ -2/6
=6* 6/-2
=-18