The mean weight of antarctic penguins found in a colony last year was 15.4 kg. In a sample of 35 penguins same time this year in the same colony the mean weight was 14.5kg. Assume the population standard deviation is 2.5kg. Find the 95% confidence interval for the population mean. Possible answers:

- (13.77, 14.53),
- (13.27, 15.43),
- (12.37, 14.35),
- (13.77, 15.43).

Thank you any help would be much appreciated!