"What share is X?" means X ÷ (the relevant total). The classic miss: dividing by a subtotal, by everything-except-X, or by a total from the wrong row — the division is right, the denominator isn't.
Questions deliberately offer several candidate totals (column totals, row totals, grand totals), and 'hidden total' variants don't print the total at all — you must build it. Under pressure, any sum that's visible feels like THE total.
Name the population before dividing: "share of WHAT?" If the total isn't printed, compute it first as its own step and write it down. Check the result direction: a share of a grand total must be smaller than the same value's share of any subtotal.
| Channel | £000 |
|---|---|
| Digital | 60 |
| TV | 130 |
| 110 | |
| Radio | 70 |
| Total | 370 |
What percentage of the £370,000 total is the Print channel?
Share = part ÷ total × 100, using the overall total as the denominator. The correct answer is 29.7%. Traps to avoid: 18.9% comes from the "wrong slice" error; 14.9% comes from the "wrong total" error; 16.2% comes from the "wrong slice" error; 42.3% comes from the "divided by others" error.
This trap appears in 46 of our questions, across: Share of total · Probability from a table · Share of hidden total · Revenue share.
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