Question

The clearness index was determined for the skies over Baghdad for each of the 365 days during a particular year (Contribution to the Study of the Solar Radiation Climate of the Baghdad Environment, Solar Energy, 1990: 7–12). The accompanying table gives the results. Class Frequency .15 - 25 8 .25 - 35 14 .35 - .45 28 .45 - .50 24 .50 -.55 .55 - .60 51 .60 - .65 106 .65 -.70 84 .70 - 75 11 (a). Draw histogram. (6). Cloudy days are those with a clearness index smaller than .35. What percentage of the days were cloudy? (c). Clear days are those for which the index is at least 65. What percentage of the days were clear? 39

Answer 1

Fox_construction of bistogram, We have two me cessary conditions: » The frequency olisterlbution is continuous 2 _All_classes_åre of equal width : If all classes are not of equal width the you need to Adjustmelut.of-frequency according to Width: So here we need adjusted frequency by wring. formula: Adjusted fregn of a class = Frequency of class Now we construct new table * Minimum Class Wide class width Frequency width 10 وره 0 class •15-25 25-135 35.45 .4.5-50 -50-55 •55 - 160 28*.05 '05 8 14 28 24 39 5) 100 24 ul Adjusted frequency 8x. 05 4 4X105 7 14 244:05 24 39 51 = 106 =84 05 39 05 306X05 05. 5.05 05 •60-165 .65 .70 •70-·75 1905 .05 Had Now, we draw a histogram acce histogram according to class and adjusted frequency on graph paper

(6) percentage of days whose index smaller than - 35 (8+14) X100= 365 22 x 100 6.03% Az 365 (0) Percentage of 04+03 x100 days whose index is al least :65 26.03% 95 X100 = 365 365