On average a supermarket sells 500 litres of milk a day with a standard deviation of 50 litres.

If the supermarket has 600 litres in stock at the beginning of a day,

i.what is the probabilitythat it will run out of milk?

ii.What is the probability that demand is between 450 and 600 litres in a day?

iii.How many litres should the supermarket stock if it wants the probability of running out to

be 0.05?

iv.How many should it stock if it wants the probability of running out to be 0.01?