Correction: Time Stamp 3:58, to find B, the p-value for a two-tailed test, we should use 2*(1-T.DIST(11.026, 18, TRUE)). To find D, we use 2*T.DIST(-7.96, 18, TRUE). Both p-values are close to 0. This is because the area to the left of -7.96, a negative number, is indeed one of the two corners we need to find the p-value, so we can just multiply the corner by 2 to get the p-value. However, the area to the left of 11.026, which is a positive number, is not one of the two corners; and we use 1 - T.DIST to find one corner first and then multiply it by 2. I'd recommend drawing a bell curve and labeling where the test statistic is to visualize the two corners. My apologies!
Correction:
Time Stamp 3:58, to find B, the p-value for a two-tailed test, we should use 2*(1-T.DIST(11.026, 18, TRUE)).
To find D, we use 2*T.DIST(-7.96, 18, TRUE). Both p-values are close to 0.
This is because the area to the left of -7.96, a negative number, is indeed one of the two corners we need to find the p-value, so we can just multiply the corner by 2 to get the p-value. However, the area to the left of 11.026, which is a positive number, is not one of the two corners; and we use 1 - T.DIST to find one corner first and then multiply it by 2.
I'd recommend drawing a bell curve and labeling where the test statistic is to visualize the two corners. My apologies!