Chapter 4

Chapter 4

1. Mathematical models

   • spreadsheets are based on a layout of rows and colums , it allows spreadsheets to be laid out in a logical and easy to follow format
   • Use of rows and columns lead to the use of sequencing and replication, replication is the copying of a cell either horizontally or vertically

2. Characteristics of spreadsheets

   • can be based on formulae and functions
   • What if questions allow user to change value and see what effect would be as end result
   • Spreadsheets can use variable and constants
   • Variable is a changeable value and the change can lead to the re-calculation of figure
   • Constants are values used in the formulae but the user cannot change

3. Advantages of modelling

   • Less risky to test a design than create it in reality and test it
   • Only one model needs to be created in a computer and that model can be altered and chaged,
     • If there was an error in a physcial model then more money would need to created to correct it
   • A computer model can be backed up and shared. Since it is stored electronically it can be backed up on a disk and sent to others
   • Computer model can be accelerated or slowed down to see effects that could not be viewed in reality e.g. explosions

4. Characteristics of a variable

   • Variable is an identifier associated with a particular cell and within this cell will be a value
   • a variable could be a cell reference e.g. C4 or cell could have a name. The value in the thing that is used

5. Characteristics of formulae

   • It is a calculation typed in by the user
   • It is the way a calculation is represented in a spreadsheet
   • use addresses of cells and mathematical operators
   • All formulas must start with an =

6. What is a function and give examples

   • A function is a command/complex formulae
   • It is a formula that is too complex or too long to expect an ordinary user to enter, they are reserved words built in
   • e.g. SUM - Adds a range of cells to give a total

7. Characteristics of rules

   • Rules are set of procedures that must be followed e.g. validation rule
   • These set of rules enable a procedure to be followed by different people

8. What if..? questions

   • attempt to find out what is going to happen in the future
   • Models recalculate automatically
   • Benefits of using a model
     • Re-calculation
     • Only cost involved is time
     • Model answer as many What if questions
   • Cost adn time involved are both likely to be less than creating a physical model
   • if error in model, it is easier to alter on a computer than a physical model

9. What is a worksheet

   • is a large grid of cells on a single sheet
   • It can be used to hold data on a single area of business

10. Workbook

    • A workbook is a collection of more than one worksheet in the same spreadsheet
    • Advantages
      • Data changed on one worksheet will be reflected across the whole workbook
      • Different access rights can be given
      • workbook is saved as a single entity

11. Row and column

    • a row is a range of cells that goes across the spreadsheet
    • A column is a range of cells that go down the spreadsheet

12. spreadsheet cells

    • a cell is an individual data store identified by a column and row indicator e.g. A4
    • Every cell is uniquely identifiable
    • Cells can be formatted and protected and hidden to stop data being altered
    • Contains labels, data and formulas and functions

13. Range

    • group of cells than can be given a name from top left ro bottom right
    • used to contain cells with similar data e.g. marks for exam