At a certain hospital, 75% of the interns receive fewer than 6 hours of sleep and report feeling tired during their shifts. At the same time, 70% of the interns who receive 6 or more hours of sleep report no feelings of tiredness. If 80% of the interns receive fewer than 6 hours of sleep, what percent of the interns report no feelings of tiredness during their shifts?
6
14
19
20
81
How can I quickly solve this? Thanks
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ssmiles08
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Let total inters = 100
75 percent of total interns who had less than 6 hours of sleep were tired.
80 percent of total interns had fewer than 6 hours of sleep which means 5 percent of interns who had less than 6 hours of sleep.
if 80 percent of total interns had fewer than 6 hours of sleep, 20 percent of the total interns had more than 6 hours of sleep.
0.7(20) = 14 percent of interns who had more than 6 hours of sleep did not feel tired.
so 14 + 5 = 19% of total interns did not feel tired. IMO C.
75 percent of total interns who had less than 6 hours of sleep were tired.
80 percent of total interns had fewer than 6 hours of sleep which means 5 percent of interns who had less than 6 hours of sleep.
if 80 percent of total interns had fewer than 6 hours of sleep, 20 percent of the total interns had more than 6 hours of sleep.
0.7(20) = 14 percent of interns who had more than 6 hours of sleep did not feel tired.
so 14 + 5 = 19% of total interns did not feel tired. IMO C.
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