Final answer:
The new process will cease to be profitable when the increased cost surpasses the savings, which occurs at t ≥ 9 based on the given functions. The answer options provided do not include this solution; therefore, the correct answer is none of the above.
Step-by-step explanation:
The question is asking when the new process developed by the factory will cease to be profitable. To determine this, we compare the savings function, S'(t) = 100 - t², with the increased cost function, C(t) = t² - 10t + 28. The process will no longer be profitable when the increased cost is greater than the savings. So, we need to find the value of t where S'(t) = C(t).
Setting the two equations equal to each other:
100 - t² = t² - 10t + 28
Bringing all terms to one side gives us:
0 = 2t² - 10t - 72
Dividing the entire equation by 2 gives us:
0 = t² - 5t - 36
Solving this quadratic equation by factoring, we get:
(t - 9)(t + 4) = 0
Therefore, t = 9 or t = -4. Since time cannot be negative, we discard t = -4.
The process will be profitable as long as the savings are greater than the costs, which occurs when t < 9. The process will no longer be profitable when t ≥ 9.
Therefore, none of the options provided (t < 2, t > 2, t = 2, or t = 5) are correct, and the correct answer should be t ≥ 9.