In: Statistics and Probability
It is believed in a renowned courier service that packages delivered at the beginning of the month are lighter than those delivered at the end of the month. As an experiment a random sample of 15 packages are weighed at the beginning of the month and it is found that mean weight was 6.25 kgs with a standard deviation of 1.18 kgs. A random sample of 12 packages have also been weighed at end of the month and it is found that mean weight was 4.86 kgs with a standard deviation of 1.14 kgs. At the 99% level of significance, test the claim that packages at the beginning of the month are lighter