This video is part of a set, so I didn’t explain that part in this video. The reason it is 0.4500 is because the bell curve has a total area of 1.00, and it is symmetric. The symmetry allows us to assume each half of the curve is 0.5 (0.5 + 0.5 = 1.00). If you have 5% or 0.05 in the upper tail, the rest of the area in that half is 0.5 - 0.05 = 0.4500
