Question

Test #3 (Chapters 5 & 6) Review If you review the material below and fully understand them you should be fine for the test. To enhance your studying, simply work through the Wiley problems as well as your Groupworks for more practice. Filters at a water treatment plant become less effective over time. The rate at which the population passes through the filters into a nearby lake is given in the table below. Estimate the total quantity of pollution entering the lake during the 30-day period by finding the lower estimate and upper estimate and averaging these values. 1. Day 0 12 18 24 30 Rate (kg/day) 7 10 13 18 35

Answer 1

If the rate of pollution entering the lake is constant, then

Total pollution that the entered the lake = Rate per day × Number of days

Now how much pollution ebtwree the lake in first 6 days?

During these days, pollution rate went from 7 to 8. If we assume 8kg/day for the first 6 days, that gives the upper-estimate for the total pollution for those days.

Similarly using upper-estimate for all 30 days,

Upper-estimate of total pollution entering the lake = (8×6)+(10×6)+(13×6)+(18×6)+(35×6) = 504 KG

Now, we get the lower-estimate by taking the lower values of rate for 6 day periods, thus

Lower-estimate of total pollution wnterien the lake = (7×6)+(8×6)+(10×6)+(13×6)+(18×6) = 336 KG

Therefore the total amount of pollution entering the lake in 30 days period is somewhere between 336 KG and 504 KG.

And we esrinate that value by taking an average of lower and upper limit.

Total pollution entering the lake = (504+336)/2 = 840 / 2 = 420 KG.