Monthly jam production at Juicy Jams is normally distributed with a mean of 56,000 liters and a standard deviation of 11,200 liters. (18 points)

1. a)What is the probability of production exceeding 70,000 liters in a given month? (3 points)
2. b)What is the probability of production being less than 30,000 liters in a given month? (3 points)
3. c)What is the probability of production being between 40,000 and 60,000 liters in a given month? (3 points)
4. d)What is the probability of production being between 60,000 and 80,000 liters in a given month? (3 points)
5. e)Juicy Jams is concerned that they may not have enough jam to meet demand. They have set a buffer of
6. 15%. What should the minimum production be? (3 points)
7. f)Juicy Jams has just purchased some more efficient equipment to produce the jam. They now believe that
8. production will be below 40,000 liters only 5% of the time. If the standard deviation is unchanged what is the new mean? (3 points)

so for question 3 you need to add your Z scores for the probability but for 4 the answer sheet says I need to subtract my z scores from each other. how do I know when to add or subtract?