A sample of 105 healthy humans showed an average body temper
Solution
Given that
n = number of healthy humans = 105
Averag body temperature (Xbar) = 98.1 0F
sample standard deviation = 0.570F
The point estimate of the mean body temperature of all healthy womans is µ = 98.10F
The 95% confidence interval for population mean is,
Xbar - E < µ < Xbar + E
Here we use t-distribution because population standard deviation is unknown.
E is the margin of error.
E = tc * s /sqrt(n)
s is sample standard deviation.
c is the confidence level = 0.95
alpha = 1 - c = 1 - 0.95 = 0.05
tc we can find by using EXCEL.
syntax:
=tinv(probability,d.f)
where probability = alpha
d.f. = n - 1 = 105 - 1 = 104
tc = 1.9830
5E = (1.9830 * 0.57) / sqrt(105) = 0.1103
lower limit = Xbar - E = 98.1 - 0.1103 = 97.99
upper limit = Xbar + E = 98.1 + 0.1103 = 98.21
95% confidence interval for population mean is (97.99, 98.21)
Yes 98.1 lies between 97.99 and 98.21.
