FIGURE P1.1 The File Structure for Problems 1-4 1. How many records does the file contain? How many fields are there per record? 2. What problem would you encounter if you wanted to produce a listing by city? How would you solve this problem by altering the file structure? 3. If you wanted to produce a listing of the file contents by last name, area code, city, state, or zip code, how would you alter the file structure? 4. What data redundancies do you detect? How could those redundancies lead to anomalies? Figure P2.4 The DealCo relational diagram 4. Identify each relationship type and write all of the business rules. 5. Create the basic Crow’s Foot ERD for DealCo. FIGURE P3.17 The Ch03_TransCo Database Tables 17. For each table, identify the primary key and the for...
2.1.14. Let X1, X2 be two random variables with joint pmf p(x1, x2) = (1/2)x1+x2 ,
ReplyDeletefor 1 ≤ xi < ∞, i = 1, 2, where x1 and x2 are integers, zero elsewhere. Determine
the joint mgf of X1, X2. Show that M(t1, t2) = M(t1, 0)M(0, t2).
2.2.6. Suppose X1 and X2 have the joint pdf fX1,X2 (x1, x2) = e−(x1+x2)
ReplyDelete, 0 < xi <
∞, i = 1, 2, zero elsewhere.
(a) Use formula (2.2.2) to find the pdf of Y1 = X1 + X2.
(b) Find the mgf of Y1.