Percentile predictor
One mock is luck; a trend is information. Enter your last few full-mock scores (out of 300, oldest first) and this fits a line through them, projects it one step forward, and converts that projection to a percentile band.
This band is WIDER than the marks-vs-percentile tool's on purpose: it carries two uncertainties at once — NTA normalisation AND whether your trend continues on exam day (±14 marks on the projection itself). A projection from your own mocks is orientation, not a promise.
A trend line can't tell you WHY the line bends.
Mock scores plateau when the same chapters keep leaking marks. The 15-question diagnostic finds which ones — that's what moves the line, not more mocks.