Statistics Expected Value Problem (all parts would be nice but c and d will suffice)?

2. Two stores sell pumpkins. At the first store the pumpkins weigh an average of 22 Lbs. with a standard deviation of 2.5 Lbs. At the second store the pumpkins weight an average of 18 Lbs. with a standard deviation of 2 Lbs. You randomly select a pumpkin from each store.

a. Find the mean difference in weights of the pumpkins.

b. Find the standard deviation of the difference in weights of the pumpkins.

c. If a Normal model can be used to describe the difference in weights between the pumpkins, what is the probability that the pumpkin from the second store is heavier than the pumpkin from the first?

d. What three assumptions must be made in order that a Normal model can be used to describe the difference in weights between the pumpkins?

i. That _________________________________________________________________________________

ii. That _________________________________________________________________________________

iii. That _________________________________________________________________________________