A survey of licensed drivers inquired about running red lights. One question asked, "Of every ten motorists who run a red light, about how many do you think will be caught?" The mean result for 865 respondents was x⎯⎯⎯ = 1.75 and the standard deviation was s = 1.86 . For this large sample, s will be close to the population standard deviation sigma, so suppose we know that sigma = 1.86 .