The following random samples are measurements of the heat-producing capacity (in millions of calories per ton) of specimens of coal from tow mines:

a) Use the level of significance ?=0.05. Test whether there is a significant difference in heat-producing capacity between the two mines. Assume the variances are equal between heat-producing capacity of two mines.

b) Use the level of significance ?= 0.05. Test whether the variances between heat-producing capacity of two mines are equal.

Mine 1---> 8260 Mine 2---> 7950 8130 8350 8070 8340 7890 7900 8140 7920 7840