An article in a scientific journal compares the low fat diet and the low carbohydrate diet.

A sample of 77 subjects was put on the low carbohydrate diet for six months. At the end of this period, the average weight loss was 4.7 Kg with a standard deviation of 7.2 Kg.

A second sample of 79 subjects was put on the low fat diet for the same period and the average weight loss was 2.6 Kg with a standard deviation of 5.9 Kg.

a) Can you conclude that the average weight loss is greatest with the low carb diet? Use a 5% threshold.

b) Can you conclude that the average weight loss with the low carbohydrate diet is more than one kilogram than with the low fat diet? Use a 5% threshold. Explain.