The rate at which pollution escapes a scrubbing process at a manufacturing plant increases over time as filters and other technologies become less effective. For this particular example, assume that the rate of pollution (in tons per week) is given by the following table. days 0| 4| 7| 10 | 14| 20 pollution rate (tons/week) || 43 | 51 | 74 93 122 | 235 (a) Write a left Riemann sum that estimates the amount of pollution emitted over the first four weeks. (Notes: (1) You must include at least two terms in your sum. (2) You do not need to evaluate the sum. (3) The units for time and pollution rate are correct.) (b) How does your left Riemann sum compare to the actually amount of pollutant emitted? Can you tell if your Riemann sum is an overestimate or an underesti- mate?

O 10 25 37 46 60 Rate (gal/sec) 500 400 | 350 | 280 200 180 Time (sec) (Calculator Permitted) The table above gives the values for the rate (in gal/sec) at which water flowed into a lake, with readings taken at specific times. A right Riemann sum, with five subintervals indicated by the date in the table, is used to estimate the total amount of water that flowed into the lake during the time period 0sis 60. What is this estimate? (A) 1,910 gal (B) 14,100 gal (C) 16,930 gal (D) 18,725 gal (E) 20,520 gal