Factor out the gcf: 21c^9−28c^6

select one:
a. 7c^3(3c^6−4c^3)
b. 7c^6(3c^3−4)
c. 7c(3c^8−4c^5)
d. 7(3c^9−4c^6)

(b) suppose that consolidated power decides to use a level of significance of α = .05, and suppose a random sample of 100 temperature readings is obtained. if the sample mean of the 100 temperature readings is x⎯⎯ = 60.990, test h0 versus ha and determine whether the power plant should be shut down and the cooling system repaired. perform the hypothesis test by using a critical value and a p-value. assume σ = 5. (round your z to 2 decimal places and p-value to 4 decimal places.)