A recent study by the Greater Los Angeles Taxi Drivers Association showed that the mean fare charged for services from Hermosa Beach to Los Angeles International Airport is $ 22 and the standard deviation is $ 3.40. We select a sample of 22 fares. What is the likelihood that the sample mean is between $ 21 and $ 23? Assume the population of fares is normally distributed (Round z value to 2 decimal places and final answer to 4 decimal places )

The mean of 22 sample is 22, and std is 3.4/sqrt(22) = 0.725, Pr(21<X<23) = Pr (-1/0.725<(X-22)/0.725<1/.725) = Pr(-1.38<Z<1.38) = Pr(Z<1.38)-Pr(Z<-1.38) = 1-2*0.08379 = 0.832