Four different types of solar energy collectors were tested. Each was tested at five randomly chosen times, and the power (in watts) was measured. The results were as follows.
Collector Power
A 1.9 1.6 2.0 1.8 1.6
B 1.7 1.9 1.8 1.7 1.7
C 1.2 0.9 1.2 0.9 1.4
D 1.5 1.0 1.4 1.3 1.4
(a) Using ? = 0.05, can you conclude that the mean power differs for different collectors?