Weights of oranges sold at a supermarket foolow a normal distribution with mean 0.22 pounds and standrad deviation 0.04 punds. If you randomly slect four oranges, what is the probability that their total weight is less than 1 pound?

z = (X-Mean)/(Standard deviation/sqrt(n))
X = 1 pound / 4 = 0.25 pounds
z = (0.25-0.22)/(0.04/sqrt(4)) = 1.5
The area under the standard normal curve left to z = + 1.5 indicates the required probability.
Required probability = 0.5000+0.4332 = 0.9332 or 93.32%