Question 1091883
a. The sample mean is normally distributed with a smaller standard deviation and the same mean as the population, 2m25s
b. The standard error of the mean is sigma/sqrt (n)=10 sec/sqrt(24)=2.04 sec. The std error is the std deviation of the sample. There is no z-value involved here.
c. z > 2.45(xbar-mean)/SE=(150-145)/2.04. This would be 0.71% or 0.0071
d. z > (138-145)/2.04=-7/2.04 or z > -3.43 or 99.97% or 0.9997
d. z>150 sec is 0.0071 from above, so we would subtract that from d to get 0.9926 or 99.26%.