Figure 7.15 on page 204 shows the frequency distribution of various values for the product of H times u for Peoria, Illinois. If the average daily emission rate for carbon monoxide for this city is 2×10 7 g/(h·mi 2 ) and the standard to be met is 10 mg/m 3 , what fraction of the time must we implement intermittent control to meet this standard? Assume that the simple box model (Sec. 6.2) applies, that the size of the city is 5 mi by 5 mi, and that the background concentration is 2 mg/m 3 .