With statistics work. sos. i might cry

You're looking for



where is the random variable representing the amount of lumber harvested. Transform this to the standard normal distribution, using



where is the mean and are the mean and standard deviation of , respectively. So the probability in terms of is




is a continuous random variable, so the above can be split up as



and consulting a table, you end up with a probability (proportion) of about 0.3311.