Estimating from a sample
The Maths Habit Handout to print
How could you find out how many blades of grass there are on a football pitch?
Count a small square, then scale up
- Population
- The whole group you want to know about.
- Sample
- A small part of the population that is checked.
| Red | Total | ||
|---|---|---|---|
| Sample | 8 | 50 | |
| Bag | 200 |
A school has 900 students. 60 students are asked and 22 cycle to school. Estimate how many of the 900 students cycle.
| Cycle | Total | ||
|---|---|---|---|
| Sample | |||
| School |
A wood has 1500 trees. In a sample of 60 trees, 14 are oak. Estimate the oak trees in the wood.
| Oak | Total | ||
|---|---|---|---|
| Sample | 14 | 60 | × 25 |
| Wood | 350 | 1500 |
Estimate 350
A stadium holds 4000 fans. In a sample of 80 fans, 52 wear a scarf. Estimate the fans wearing a scarf.
| Scarf | Total | ||
|---|---|---|---|
| Sample | 52 | 80 | |
| Stadium | 4000 |
Estimate 2600
A wood has 1500 trees. In a sample of 60 trees, 14 are oak. Estimate the oak trees in the wood.
| Oak | Total | ||
|---|---|---|---|
| Sample | 14 | 60 | |
| Wood | 1500 |
Estimate 350
A warehouse has 2400 boxes. In a sample of 120 boxes, 9 are damaged. Estimate the damaged boxes.
| Damaged | Total | ||
|---|---|---|---|
| Sample | |||
| Warehouse |
Estimate 180
A wood has 1500 trees. In a sample of 60 trees, 14 are oak. Estimate the oak trees in the wood.
| Oak | Total | ||
|---|---|---|---|
| Sample | 14 | 60 | |
| Wood | 1500 |
Estimate 350
A library has 7200 books. In a sample of 90 books, 23 are hardback. Estimate the hardback books in the library.
| Hardback | Total | ||
|---|---|---|---|
| Sample | |||
| Library |
Estimate 1840
A wood has 1500 trees. In a sample of 60 trees, 14 are oak. Estimate the oak trees in the wood.
| Oak | Total | ||
|---|---|---|---|
| Sample | 14 | 60 | |
| Wood | 1500 |
Estimate 350
A factory makes 6000 bulbs. In a sample of 150 bulbs, 4 do not work. Estimate the bulbs that do not work.
| Do not work | Total | ||
|---|---|---|---|
| Sample | |||
| Factory |
Estimate 160
A wood has 1500 trees. In a sample of 60 trees, 14 are oak. Estimate the oak trees in the wood.
| Oak | Total | ||
|---|---|---|---|
| Sample | 14 | 60 | |
| Wood | 1500 |
Estimate 350
A cinema sells 2000 tickets. In a sample of 40 tickets, 26 are for adults and the rest are for children. Estimate the tickets for children.
| Children | Total | ||
|---|---|---|---|
| Sample | |||
| Cinema |
Estimate 700
Answer sheet
Kai asks 10 friends from his football team which sport they like best. He uses the results to estimate for his whole school. Give one reason his estimate may not be reliable.
The sample is small and not randomA 1 m² square of a football pitch has about 90 000 blades of grass. The pitch has an area of 7000 m². Estimate the number of blades of grass on the pitch.
630 000 000
In a sample of 30 bulbs, 4 do not work. Estimate how many of 900 bulbs do not work.
12018 out of a sample of 80 homes have solar panels. Estimate how many of 2000 homes have solar panels.
450Nia asks 12 people in a library how many books they read, to estimate for her whole town. Why may this not be reliable?
Small sample; library users read more