Estimation

NOTEstimation is Just guessing

It Is a reasonable rough approximation, fairy accurate, quick calculation that is a guide to the actual answer.

Example: What is half of 1578?

Let’s round this to 1600. Half of 1600 is 800.

So half of 1578 is about 800

Question: Will the actual answer be more or less than 800?

Is a skill that you will have to demonstrate

EstimationHalf of 1578 is :- 789 Just less than 800

Why is the correct answer just less than our estimate?

Because we rounded up Our estimate will be bigger than the actual answer

Similarly

If we had rounded downOur estimate would be lower than the actual answer

EstimationPrice list

Pint of larger………………..£2.85

Pint of bitter……………..…£2.65

Glass of wine………………£2.20

Lemonade…………………….80p

Fruit based drink…………..£2.45

In a bar you buy the following round of drinks:

2 pints of larger, 2 glasses of wine 1 fruit based drink 1 and a half pints of bitter

Roughly how much will you spend?

Times up!

No calculators!

EstimationPrice list

Pint of larger………………..£2.85

Pint of bitter……………..…£2.65

Glass of wine………………£2.20

Lemonade…………………….80p

Fruit based drink…………..£2.45

In a bar you buy the following round of drinks:

2 pints of larger, 2 glasses of wine 1 fruit based drink 1 and a half pints of bitter

Roughly how much will you spend?£16.50

EstimationPrice list

Pint of larger………………..£2.85

Pint of bitter……………..…£2.65

Glass of wine………………£2.20

Lemonade…………………….80p

Fruit based drink…………..£2.45

In a bar you buy the following round of drinks:

2 pints of larger, 2 glasses of wine 1 fruit based drink 1 and a half pints of bitter

£16.50

2 pints of larger +

2 glasses of wine +

1 fruit based drink +

1 and a half pints of bitter

£6.00 + £4.00 + £2.00 + £3.00 + £1.50 =

EstimationPrice list

Pint of lager………………..£2.85

Pint of bitter……………..…£2.65

Glass of wine………………£2.20

Lemonade…………………….80p

Fruit based drink…………..£2.45

In a bar you buy the following round of drinks:

2 pints of lager, 2 glasses of wine 1 fruit based drink 1 and a half pints of bitter

Because we rounded up and down we cannot be certain if the actual answer will be above or below £16.50.

What do you think?

Work out the actual answer Compare with the estimate

Are you sure your answer is right?

EstimationWeekly shopping bill

£165.58

£158.75

£186.30

£142.52

£215.85

On the left are five weekly shopping bills. What would be a good way of estimating next weeks bill?

The mean average

(add link to averages)

Work out the mean average £173.80

How much will be spent in a whole year?

Assuming the prices don’t go up!

Remember averages are a way of estimating NOT accurately calculating the actual amount.

Click when ready

Estimation

Formula