\fOH Math 229 Lab 22: Section 15.5 4. A new smog-control device will reduce the output of sulfur oxides from automobile exhausts. It is estimated that the rate of savings (in millions of dollars per year) to the community from the use of this device will be approximated by S'(x) = -13 + 4r +8, after a years of use of the device. The new device cuts down on the production of sulfur oxides, but it causes an increase in the production of nitrous oxides. The rate of additional costs (in millions of dollars per year) to the community after r years is approximated by C'(x) = 2572. (a) For how many years will it pay to use the (b) What will be the net savings over this period new device? of time ? round 2 decimals 5. Kirk Enterprises has an expenditure rate of E'(x) = e0.1 dollars per day and an income rate of I'(r) = 98.8 - e0.1z dollars per day on a particular job, where a was the number of days from the start of the job. Profit will be maximized is the job ends at the optimum time. (a) What is the optimum number of days for (b) What is the maximum profit for the job? the job to last? (Round to the nearest day) need to two decimals Page 2