Please help me by answering this question , quickly

A sweet shop sells chocolate which appear, at first sight, to be identical. The chocolates are all in the shape of circular disks and the diameter, in millimetres with mean 275m. The sample of 19 chocolates were taken and found the diameters are as follows. 279 263 284 277 281 269 266 271 262 275 266 272 231 274 279 277 267 269 275 (a) State any necessary assumptions. (1 mark) (h) Test the claims that mean diameter is 275 mm at 10% signicant level (i) State the test hypotheses. (1 mark) (ii) State the test statistic and draw the rejection/critical region. (4 marks) (iii) What is your conclusion based on (ii). (2 marks) (c) What changes would happen to your test if it is known that the standard deviation of the diameter was 5 mm? (2 marks)