The U. S. Postal Service is to deliver a letter to a certain postal ZIP 4 code. Find the probability that the ZIP 4 code is correct if the sender (a) randomly chooses the code, (b) knows the five-digit code but must randomly choose the last four digits, and (c) knows the five-digit code and the first two digits of the plus 4 code.

Anne found the 10th term of the following sequence. her steps are shown below. 3, 7, 11, 15, … 1. common difference = 4, a1 = 3 2. an = 3 + (n - 1)4 3. an = 3 + 4n - 4 4. an = 4n - 1 5. a10 = 4(10) – 1 6. a10 = 39 analyze anne’s work. is she correct? if not, what was her mistake? yes, she is correct. no, she needed to find the common ratio because it is a geometric sequence. no, she substituted the wrong values into the rule to find the equation that represented the sequence. no, she solved for the 10th term incorrectly.