Using a spreadsheet to answer "What if" questions

Load the spreadsheet from the shared area (only if you're at Arden) or download it from this site.

After each question you will need to re-set the values in the spreadsheet or you will get different answers to me. Look at the screenshot below to remind you of how it started out or use Edit > Undo to go back to the original version.

look at the original values of the spreadsheet

You can use goal seek to help find some answers quicker. To find it, click on Tools > Goal Seek. This brings up a little box like this.
goal seek box

Set Cell. Click on the cell that has the number you want to change to something - the result. E.g. the profit cell
To value. Fill in the number you want to get - e.g. 0 for profit/loss.
By changing. Click on the thing that you can control - usually the number the question is asking for. E.g. Estimated number of people.

When you click OK, Goal Seek will find the answer for you and tell you what it is. You have to now think whether the answer is sensible - if it is a number of people it has to be a whole number, if it's a price it can only have two numbers after the decimal point.

Fill you answers in the box on this page. Read the feedback and change your answer if you need to.

Ask your teacher if you get stuck or need help with this!

What if the raffle prizes go up to £200 and the cost for hiring the rides goes up to £800. What will the profit/loss be then?
Have you re-set the values in the spreadsheet yet?

When you have, find out what happens if the entrance cost £3 per person and 227 people came.

Tell me how much profit or loss would be made.
Remember to re-set the spreadsheet values!

"Break even" means that the profit/loss is as close to £0 as possible. If we can't be exact, we would prefer a small profit than any loss. It help us be sure that we won't end up broke after the school fete.

What if everybody who comes buys two teas or coffees and we want to "break even"? How many people need to come?

Use "trial and error" or goal seek to find the answer to this question.
The Headteacher wants a profit of £3000 to give to charity but also would like to have free entry. How many people will need to come for that to happen?

Don't forget to re-set your spreadsheet before answering and use Goal Seek to make it easier!
The price of rides is going to go up to £1.What price will we need to charge for the games to make £4500 profit?
The parent who is running the raffle wants to make £500 for the school. If 300 people come and the raffle price stays the same, how many goes will each person have to have to make that much money?
What if the PA system and the rides each cost £800 and just 150 people came? We have to make a profit of £500, what should we charge for rides?
What if all the plants cost £1 but everyone bought 3 - how many people have to come to give us a profit of £5500?

Using a spreadsheet to answer "What if" questions

Finding out what happens at the school fete