Finite Math - Probability

Need assistance with following problem along with steps to arrive at solution/answer. Three envelopes are addressed for 3 secret letters written in invisible ink. A secretary randomly places each of the letters in an envelope and mails them. What is the probability that at least 1 person receives the correct letter?

Finite Math - Problem with Excel Spreadsheet Attachment

At the start of the year, a company wants to invest excess cash in one-month, three-month and six-month Certificates of Deposit (CD's). (Purchase price and yields for the different CD's appear in the table below). The company is somewhat conservative, however, and wants to make sure that it has a safety margin of cash-on-hand each month; i.e., cash-on-hand left over from the previous month / available at the outset, plus principal and interest from CDs that have become due, minus investments made at the start of the month, must be no less than the month's safety margin. The size of the monthly safety margins are as follows: Jan $175,000 Feb $90,000 Mar $80,000 Apr ... click for more

False positives

An experimental test to detect a particular type of cancer indicates the presence of cancer in 90% of individuals known to have this type of cancer, and in 15% of individuals known to be cancer-free (false positive). One hundred individuals volunteer to take the test. Of the 100, 60 are known to have the cancer, and 40 are known to be cancer-free. If the test indicates that one of the individuals, randomly chosen, has the cancer, what is the probability that he or she is actually cancer-free? Need Assistance solving above problem. Please provide step by step in solving problem providing solution/answer

Linear Programming (Inequalities)

Linear Operators - Simplex Method. Please see the attached problems. Thank you.

Sets

Describe set in words- B ∩ D