1.1. Margot, a biologist, is researching the lengths of snails that are bred in captivity.  It is known that the standard deviation of the length of a snail in captivity is 7.2 mm.  Margot claims that the mean length of snails is less than 60 mm.  Taking 20 snails as a sample, Margot calculates the sample mean as 56.1 mm.

Stating your hypotheses clearly, test Margot’s claim using a 1% level of significance.

1.2. State two assumptions that you made whilst carrying out the test in part (a).