4. The weights of sacks of potatoes are normally distributed. It is known that one in five sacks weigh more than 6 kg and three in five sacks weigh more than 5.5 kg .
i. Find the mean and standard deviation of the weights of potato sacks.
ii. The sacks are put into crates, with twelve sacks going into each crate. What is the probability that a given crate contains two or more sacks that weigh more than 6 kg ? You must explain your reasoning clearly in this question.
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