CS101 - Introduction to Computing - Lecture Handout 22

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Spreadsheets

Today’s Lecture:

Spreadsheets

It was the first among the four lectures that we plan to have on productivity software
We learnt about what we mean by word processing and also desktop publishing
We also discussed the usage of various functions provided by common
Second among the four lectures that we plan to have on productivity software
This 2nd lecture is on spreadsheets
We’ll learn about why we are interested in spreadsheets
We’ll discuss the several common functions provided by popular spreadsheet SW programs

Business Plan for a New Software Development Company

The information provided in this business plan is confidential. Please do not disclose it without checking with me first. Thanks.

Business Plan

Spreadsheets

Electronic replacement for ledgers
Used for automating engineering, scientific, but in majority of cases, business calculations
A spreadsheet - VisiCalc - was the first popular application on PC’s.
It helped in popularizing PC’s by making the task of financial-forecasting much simpler, allowing individuals to do forecasts which previously were performed by a whole team of financial wizard

What Can They Do? (1)

Can perform calculations repeatedly, accurately, rapidly
Can handle a large number of parameters, variables
Make it easy to analyze what-if scenarios for determining changes in forecasts w.r.t. change in parameters

What Can They Do? (2)

Are easy to interface with other productivity SW packages
Easy to store, recall, modify
Make it is easy to produce graphs:
Graphs reveal the knowledge contained in data with greater clarity and ease as compared with data arranged in rows and columns
Modern spreadsheet programs can be used to display data in a variety of graphical formats

The Structure of A Spreadsheet

Collection of cells arranged in rows and columns
Each cell can contain one of the following:Numbers
Text
Formulas
These cells display either the number or text that was entered in them or the value that is found by executing the formula

Connecting Two Cells

Connecting Two Cells

Connecting Two Cells 1

Connecting Two Cells 2

Goal Seek

Goal Seek in Excel

When you use the Goal Seek command, Excel changes the value in one cell until the value in a second cell reaches a number that you desire. For instance, if you had a spreadsheet that calculated profit for the Bhola eService from a variety of inputs, including employee numbers, expenses, products sold, price of products, you might use goal seek to define your break-even price of products. You would tell the computer to change price of products until Profit was zero (break-even), and you would do that using Tools, Goal Seek.
To use Goal Seek, go to the Tools command. If Goal seek . . . is not an option, you must first go to Add-ins (also under Tools), and select Goal Seek. Once Goal Seek is loaded, choose it under Tools.

In Goal Seek there will be three boxes to fill in.
The first says "Set cell." Enter the cell address (or click on the cell) of the cell whose value you want to fix or set to a specific number (i.e. Profit cell). This cell must contain a formula or function. Otherwise it will not be linked to the cell you will be changing to obtain zero profit.
The second says "To value." Enter the appropriate value you wish to see in that "Set" cell (i.e. 0 if you want the Profit to come out zero).
The third says "By changing cell." Enter or click on the cell you want Goal Seek to change to obtain the zero profit. (i.e. milk price). This cell must not be a formula or function. Then click "okay."
At this point Goal Seek will show you the answer. For instance, Profit will now be zero and the Milk Price cell will have changed to another price (maybe 11.86) to make Profit=0. You can accept the change or you can cancel the Goal Seek and return to the previous numbers. Often you just want to take note of the new numbers and cancel. If you accept and change your mind, click Undo.

Things that you must remember!!

Make sure the "Set Cell" cell is a formula or function or cell reference.
Make sure you have set that sell to a reasonable number.
Make sure the "By Changing Cell" cell is a number or blank, and not a formula, function or cell reference like =C5.

Make sure there is a link by formulas between the two cells you entered in the Goal Seek.
However complicated the link might be, they must be related for the Set cell to be changed by the Change cell.
Finally, make sure your formula in the "Set Cell" cell is correct (as well as all others).

Simple Example

Assume the following cells. We will use Goal Seek to find a number to make the sum=150.
A2 = 25
A3 = 40
A4 = SUM(A2:A3) which is showing 65
In Goal Seek:
Set Cell: click on A4
To Value: enter 150
By Changing Cell: click on A3
The sum in A4 should now be 150, and A3 should have become 125 for that to happen.

Solving Equation: f(x) = x2 + 2x + 1 = 0

  • Write the formula in a cell e.g. A2

formula in a cell

  • Select the goal seek option

goal seek option

  • In the ‘set cell’ input field write the cell number that needs to be changed I.e. a2
  • In the ‘to value’ field enter the value we want the cell a2 to have i.e. 0

goal seek

  • This shows the that the target was to have 0 value but excel could calculate for 0.0004 value
  • On pressing Ok we will get->
  • Here the value of a1 is 0 97 which is almost equal

goal seek status

Hence to get the value of the given function as 0 the value of x should be 1
Which is the solution of the equation
f(x) = x2 + 2x + 1 = 0
links
Following are some urls for the goal seek ;
http://www.oootraining.com/QwikAndDirty/QwikAndDirtyExcelWeb/DataAnalysis/
Using_Goal_Seek/Using_Goal_Seek.htm
The Best Feature: Undo
Allows you to recover from your mistakes
Allows you to experiment without risk
Getting On-Screen Help
All spreadsheets generally have some form of built-in help mechanism
To me, it seems like that many of those help-systems are designed to be “not-veryhelpful”:
they make finding answers to simple questions quite difficult
Nevertheless, do try them when you are searching for answers

I’ll now demonstrate the use of spreadsheets with the help of several examples

Formulas
Sorting
Conditional formatting
Graphs
Goal seek

Today’s Lecture was the …

Second among the four lectures that we plan to have on productivity software
This 2nd lecture was on spreadsheets
We learnt about what we mean by spreadsheets
We discussed the usage of various functions provided by common spreadsheets
Focus of the Next Productivity SW Lecture: Presentations
To become familiar with the basics of multimedia presentations
To become able to develop simple presentation with the help of presentation software