Normal distribution and probabilities Factory produces envelopes, and an envelope's weight (unit is a gram) X follows a normal distribution (1,99 , 0.05²). a) What is the probability that envelope picked at random weighs at least two grams? b) What is the probability, that a package of hundred envelopes weighs over 200 grams? c) A4-paper sheet is put into a randomly picked envelope. The paper sheet is following a normal distribution (4.98 , 0.04²). What is the probability that the envelope's total weight stays bellow seven grams?