We Wish to See If the Electronic Control Indicating the Oven

We wish to see if the electronic control indicating the oven temperature for a certain model oven is properly calibrated.Four ovens of this model are selected at random.The electronic control on each is set to 300°F;after 1 hour,the actual temperature of each is measured.The temperatures measured are 305°F,310°F,300°F,and 305°F.Assume that the distribution of the actual temperatures for this model when the electronic control is set to 300°F is Normal.To test if the electronic control is properly calibrated,we will test the following hypotheses: H₀: $\mu$ = 300 versus H_a: $\mu$ $\neq$ 300.Assume the standard deviation for the distribution of actual temperatures for all ovens of this model when the electronic control is set to 300°F is $\sigma$ = 4.At the 5% significance level,what is the power of our test when,in fact, $\mu$ = 310°F?

A) 0.0345
B) 0.9655
C) 0.9959
D) 0.9988