Environmental Science & Technology (Oct. 1993) reported on a study of insecticides used on dormant orchards in the San Joaquin Valley, California. Ambient air samples were collected and analyzed daily at an orchard site during the most intensive period of spraying. The thion and oxon levels (in ng/m3) in the air samples are recorded in the table, as well as the oxon/thion ratios. Compare the mean oxon/thion ratios of foggy and clear/cloudy conditions at the orchard using a test of hypothesis. Use α = .05.

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ORCHARD Oxon/ Date Condition Thion Oxon Thion Ratio Jan. 15 Fog 38.2 10.3 .270 17 Fog 28.6 6.9 .241 18 Fog 30.2 6.2 .205 19 Fog 23.7 12.4 .523 20 Fog 62.3 (Air sample lost) 20 Clear 74.1 45.8 .618 21 Fog 88.2 9.9 .112 21 Clear 46.4 27.4 .591 22 Fog 135.9 44.8 .330 23 Fog 102.9 27.8 .270 23 Cloudy 28.9 6.5 .225 25 Fog 46.9 11.2 .239 25 Clear 44.3 16.6 .375