TARA data extraction: tables and graphs
Read the question before the table. Mark the one or two cells it needs, check the units in the headings, then calculate. You have about 109 seconds a question and no calculator.
Four steps
| Step | Do this |
|---|---|
| 1. The question | Write the quantity and unit it asks for. |
| 2. The cells | Find the rows and columns that give it. Ignore the rest. |
| 3. The units | Per month or per year? Thousands or units? Per cent or percentage points? |
| 4. The check | Is the answer the right size and in the asked-for unit? |
A table with mixed units
Worked example Monthly income from three plans
A gym's members and fees are shown below. What is its total membership income in one month, counting each annual member at one twelfth of the annual fee?
| Plan | Members | Fee |
|---|---|---|
| Monthly | 240 | £30 per month |
| Annual | 180 | £300 per year |
| Student | 120 | £18 per month |
Monthly: . Annual: . Student: . Total: £13,860.
Why this works: Put every fee into the same unit, per month, before adding.
Why the tempting route fails: Adding the annual fee as written gives £63,360: a year of annual fees mixed with a month of the others.
A change over time
Worked example The biggest fall
A reservoir holds 8,000 megalitres when full. On the first of each month it was 64% full in March, 52% in April, 46% in May and 31% in June. In which month did it lose the most water, and how much?
Falls: March points, April , May . The largest is May: of megalitres.
Why this works: The loss in a month is the fall from its start to the next month's start: May, 1,200 megalitres.
Why the tempting route fails: June has the lowest level, but the question asks about the biggest fall, not the lowest point.
Where marks go
- A heading in thousands: 4.5 means 4,500.
- Percentage points against per cent: 12% to 15% is 3 points, but a 25% rise.
- A total row that already includes the rows above it.