Question

In: Math

A certain business keeps a database of information about its customers. A. Let C be the...

A certain business keeps a database of information about its customers. A. Let C be the rule which assigns to each customer shown in the table his or her home phone number. Is C a function? Explain your reasoning.

Expert Solution

If we assume that every person has

(i) a home phone number

(ii) no more than one home phone number

then and only then rule is a function.

Let us denote the people by , where stands for the first name in the book, for the second name, etc. Let the corresponding phone numbers be denoted by , where is the phone number of , is the phone number of and so on.

If for any and if , i.e. the phone numbers of and are different then and are two different people because one person is assumed not to have more than one home phone number.

So, .

Thus, we have for any . Taking the contrapositive we get for any . So is a function.

But if any person, say is allowed to have more than one phone numbers, then the value of is not unique. Therefore does not become a function in such a case.

Also if some person does not have a home phone number, then does not exist, and therefore does not become a function in such a case.

P.S.: Please upvote if you have found this answer helpful.

milcah answered 2 years ago

For customers purchasing a refrigerator at a certain appliance store, let A be the event that...

For customers purchasing a refrigerator at a certain appliance store, let A be the event that the refrigerator was manufactured in the U.S., B be the event that the refrigerator has an icebreaker, and the event that the customer purchased an extended warranty. Relevant probabilities are: P(A) = 0.70 P(B|A) = 0.85 P(B|A ′ ) = 0.75 P(C|A ∩ B) = 0.75 P(C|A ∩ B′ ) = 0.5 P(C|A′ ∩ B) = 0.6 P(C|A′ ∩ B′) = 0.25 b. What...

How to generate database diagram for a database that stores information about the downloads that users...

How to generate database diagram for a database that stores information about the downloads that users make. Each user must have an email address, first name, and last name. Each user can have one or more downloads. Each download must have a filename and download date/time. Note: I want steps on how to generate this diagram using oracle SQL developer Each product can be related to one or more downloads. Each product must have a name.

Suppose that a certain authority is running a (publicly accessible) database of users’ public keys. Let...

Suppose that a certain authority is running a (publicly accessible) database of users’ public keys. Let us define the following procedure for revoking a public key from the database. When a user Alice claims that the secret key skA corresponding to his public key pkA was stolen, she sends to the authority the statement “Revoke Alice’s public key pkA” which is signed using skA . Upon receiving such the statement, the authority revokes pkA from the database. Explain why it...

A company creates a database for its customers in which each customer is identified by their...

A company creates a database for its customers in which each customer is identified by their phone number. In this discussion, explore whether or not this is a function with your classmates. In your first post, address the following: Assign one variable as the input and the other variable as the output for this scenario. Is this relation a function? Justify your answer using the definition of a function, and explain your reasoning carefully. Do you think this is a...

Your company maintains a database with information on your customers, and you are interested in analyzing...

Your company maintains a database with information on your customers, and you are interested in analyzing patters observed over the past quarter. 23% of customer in the database placed new orders within this period. However, for those customers who had a salesperson assigned to them, the new order rate was 58%. Overall, 14% of customers within the database had salesperson assigned to them. a) Draw a contingency table for this situation. b) What percentage of customers in the database placed...

could a business use it information technology to increase switching costs and lock in its customers...

could a business use it information technology to increase switching costs and lock in its customers and suppliers? Use business examples to support your answer

Benis firm has hired you to develop a database to keep information about its sales offices....

Benis firm has hired you to develop a database to keep information about its sales offices. It has a number of sales offices in several towns. We need to store unique office number and location for each sales office. Each sales office is assigned to one or more employees. You need to store the following information for each employee; unique employee id, employee name, salary and phone number(s). An employee must be assigned to only one sales office. For each...

A certain retail store bases its staffing on the number of customers that arrive during certain...

A certain retail store bases its staffing on the number of customers that arrive during certain time slots. Based on prior experience this store expects 32% of its customers between 8:00 am and 12:00 pm; 21% of its customers between 12:00 pm and 4:00 pm; 35% of its customers between 4:00 pm and 8:00 pm; and 12% of its customers between 8:00 pm and midnight. On a certain day, the store had 214, 198, 276, and 134 customers in those...

A certain store gives its customers a discount on the goods they buy based on a...

A certain store gives its customers a discount on the goods they buy based on a peculiar manner. The discount percentage is equal to each customer's remainder of weight to age, weight % age. The maximum discount percentage allowed is 10. If the remainder is greater than 10, the discount percentage is recomputed as the remainder of 10. For example, a customer whose weight is 175 lbs and age 61, buys an item costing $60.97. The discount percentage = 175...

For this part, assume you are entering information about transactions into their relational database. You will...

For this part, assume you are entering information about transactions into their relational database. You will be entering financial information, but you will also need to consider the other types of information Big Marker would want to know about that event. You will also utilize what you have learned to identify internal controls specific to each transaction. The transactions are as follows: a. Billed 30 communities for monthly dues of $600 (each). b. Borrowed $10,000 from First National Bank with...