If it takes on average 3 minutes to get dressed, then it takes 15 minutes total on the school week because 5 x 3 = <<15=15>>15
Thus far this week it has taken him 13 minutes to get dressed because 2 + 4 + 3 + 4 = <<13=13>>13
To tie his previous method, he needs to take 2 minutes on Friday because 15 - 13 = <<15-13=2>>2
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