The weight w grams of a certain species of bird is normally distributed. the heaviest 10% weigh more than 400 grams and the lightest 5% weigh less than 300 grams.

1) Find the mean and the standard deviation of the weight.

2) A bird is picked at a random. Calculate the probability that the bird weighs more than 380 grams.

3) The weights of a random sample of 50 birds are found and the mean sample weight is calculated. Find the probability that is less than 350 grams.