Monday, 7 January 2013


by Mr Johari

A function has input and output. A good analogy of this would

be a vending machine.

  1. Explain further why this analogy is used to depict a function?
  2. Can you think of other analogy?
  3. What are the assumptions made?


  1. The vending machine is like a function as when we insert our money and the product number in, we would get a snack.
    The money/product number is our input, and the snack we get is our output.

    Another analogy would be like humans. If we feed humans a certain food, the waste that we get would also be different. The food we feed ourselves is an input, while what we release is an output.

    The assumptions made here is that we would get an output. If the vending machine does not release a snack (meaning that the input makes the rule invalid), the function would not function as it is supposed to function.

  2. 1. When you press buttons, you give an input to the vending machine. The machine will then give a food item based on what you input, similar to a function giving you an output based on your input.
    2. A computer keyboard prints something on the screen depending on what buttons you press.
    3. The vending machine is working, and is consistent in giving the right food item depending on the input.

  3. 1. A function will give you the value of an unknown based on what values you give the function and the rules that it must follow. In the case of a vending machine, it will give you the value of the unknown (which is the drink/snack) based on the values you give it (the amount of money you put in) and the rules that it must follow (the price of each product).

    2. A human. We obtain input through events that happen around us (input) and our morality and logic act as the rules that we use to decide on what actions we should take (output)

    3. We assume that there is no cheating or misuse involved when someone uses the machine.

    - Farrell

  4. 1. Let the cost of the item be x and the item be y .
    Here, x = y is the rule of the vending machine where the money is the input and the item is the output.

    2. Another analogy of a function would be maybe the work that we do everyday regardless of homework or any mode of work. The results would be the output while the amount of effort we put in would be the input.

    3. One of the assumptions made is that the input would be equal to the output , or the equation connecting them would be correct. Another way of saying is that , linking back to the vending machine, if we pay the amount of money (input) , we must have the item (output) which has the cost to the amount of money we put in, not more or less or else this function will not work.

  5. 1) The analogy is used as you have to give a coin (the input) to receive the drink/snack (the output).

    2) If you eat something (the input), it would be converted to energy (the output)...

    3) We are assuming that the function of the machine would remain the same without change

  6. 1. When we put money into a vending machine as an input, we will get what we want to buy as an output. Similarly, when you put a number in a function as an input, it transform the number into another number as an output using its present rule.

    2. When we eat something as an input, it will have to leave our body as an output.

    3. The rule of the function stays the same.

    1. Good explanation on how the vending machine depicts a function. The other analogy you gave is a appropriate one. The assumption you made is relevant. Good job. (:

  7. 1. When you put in a coin, it allows you to input your number into the machine to choose your choice and have it come out to you as an output.

    2.Computer(when you type in words,they appear on the screen as output) , Speaker (you input info and it comes out as sound)

    3. The machine is not spoilt, so that you will receive a correct output with your valid input.
    That you keyed in a valid input, if you can only select numbers 1-15, you can't input something outside of that.
    That you put the right amount of money into the machine, so you can get the right output, not an additional output (change) , or no output at all(not enough money).

  8. 1) The input number would be the money and then the customer would enter the rule by selecting which item he wants and he will get the output of the item itself.

    2) When a person is studying, the input would be the amount of effort he chooses to put in. The rule would be how efficiently he studies and the output would be his final grade in the end.

    3) There will be no random factor.

  9. 1) A vending machine has an input and output too, like a function. The input of a vending machine in the money and the output is the snack or drink.

    2) Another analogy is a typewriter. You type and the typewriter prints it on a piece of paper.

    3) The vending machine is working is good condition.

  10. 1. This analogy is used to depict a function as money and coins are placed within the machine, which is the input, the machine dispenses the product, thus there is an output.

    2. Another analogy would be a pen. The ink that is refilled is the imput, and the output is the ink that is used to write our assignments and essays.

    3. The assumptions made here is that the input and output must be equal.

  11. 1. The amount of money and the buttons to press will determine the kind of item you will get, what you put in (input) will determine what you get (output) similarly in functions, the input determines the output.
    2. Another analogy is a student taking an maths exam, the marks are given depending on what you write.
    3. The vending machine is working.

  12. 1. The coins is the input and the snacks is the output. In math, the input the original number while output is the result. The input gets changed by the equation and the output will be the answer/ snacks.

    2. Different toys are mass produced in a factory by a company has to be produced in colours. Toys are made without colours and go through a colouring machine that colours the toy. The toy is the original number while colour is the equation. The output is the coloured toy, depending on which toy it is as well.

    3. We have to assume that the vending machine is not faulty.

    1. 1. In conclusion, the input and the output would be according to the rule/function and increase/decrease accordingly.

      2. Its good.

      3. This is quite vague as faulty would mean a lot of things. Maybe buttons spoilt?

  13. 1. A vending machine is used to depict a function because whenever you input in some coins, a snack of your choice, depending on your input will come out as an output.
    2. Another analogy would be your test results. The input would be the effort you put in and the results would be the output.
    3. Assumptions made would be that the vending machine is having no technical problems, there are coins for chan and it is filled with snacks.
    Assumptions made in the second example would be that the person taking the test is mentally well.

  14. 1. Let the money you put into the vending machine be your equation .
    Let the object that comes out be the answer to your equation .
    If you insert your 'money' into the vending machine and press a number , despite how many times you press it , it will still result in the same gain . Thus , your input (the number you select) will always result in the same object coming out of the machine . Therefore this can be used to depict a function/pattern .
    2. Let our daily routine be the equation . Depending on the day our work may differ in importance but we are still doing the same work . So the day results in which work we are doing based on whats due the next day .
    3.For the vending machine , we are assuming that there is a object for every number and that they are not being repeated . The vending machine also has to be working properly and consistently .

    1. I don't think our daily routine can be an analogy, because our daily routines can change unexpectedly, even though the work we do may be the same, for example, if we reorder the tasks that we need to do, our routine has changed, but we still get the same things done

  15. 1. It works similar to what a function is. The input being the money we insert and the output being the designated item from the vending machine.
    2. An analogy of a function would be a tap. Water comes out when you switch it on.
    3. One assumption would be that the vending machine has no faults and is working perfectly fine.

  16. 1) A function which is relation between a set of inputs and a set of outputs, just like a vending machine in which putting in money in the vending machine results in a drink coming out

    2) Another analogy would be eating.The more you eat which is the input, the fatter you would get which is the output.

    3) The vending machine would dispense according to the amount of money you put in