A crayon manufacturer is comparing the effects of two kinds of yellow dye on the brittleness of crayons. Dye B is more expensive than dye A, but it is thought that it might produce a stronger crayon. Four crayons are tested with each kind of dye, and the impact strength (in joules) is measured for each. The results are as follows: Dye A: 1.0 2.0 1.2 3.0
Dye B: 3.0 3.2 2.6 3.4

Required:
a. Can you conclude that the mean strength of crayons made with dye B is greater than that of crayons made with dye A?
b. Can you conclude that the mean strength of crayons made with dye B exceeds that of crayons made with dye A by more than 1 J?