Give a backward-chaining proof of the sentence 7 ≤ 3 + 9. (be sure, of course, to use only the axioms given here, not anything else you may know about arithmetic.) show only the steps that leads to success, not the irrelevant steps.

b. give a forward-chaining proof of the sentence 7 ≤ 3 + 9. again, show only the steps that lead to success.

(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.)