The table below shows the total income tax paid by an individual at different levels of gross annual income.
| Annual income (£) | Total income tax paid (£) |
|---|---|
| 18,000 | 1,200 |
| 28,000 | 3,200 |
| 48,000 | 8,800 |
| 78,000 | 20,800 |
What is the marginal tax rate for an individual whose annual income increases from £28,000 to £48,000?
18.3%18.3\%18.3%
28.0%28.0\%28.0%
40.0%40.0\%40.0%
11.4%11.4\%11.4%
