text: probility question? test the claim that the mean body temperature of healthy sdults is 98.6 degrees f where a sample of size 106 yielded  x bar= 98.20 and s=.62 use alpha=.01 this question is from the triola textbook, isn't it?!?  if the average temperature is 98.6 then u = 98.6 is the null hypothesis. the opposite, u not equal to 98.6 is the alternate. we will consider the null hypothesis disproven if your sample falls in the most extreme 1% of values - either the top 0.5% or the bottom 0.5%. to cut 0.5% off the normal curve, use a z-score of +/-2.57.  (we only need -2.57 since the sample mean is below the null hypothesis mean). use a standard deviation of 0.62/sqrt(106)=0.0602 z = (x-u)/s -2.57 = (x-98.6)/0.0602 x = 98.6 -2.57*0.0602 x = 98.44 is the lowest sample mean we would expect from a population with mean 98.6 since our sample mean is lower, we do not accept that the population mean is 98.6 so we reject the null hypothesis. the mean body temperature of healthy adults is not 98.6  are you at nobles, by any chance?