A Red Rock question, fully worked
One question. The full working.
The right change. The wrong base.
A generated CaseStar paper with an illustrative answer, marked by our Red Rock grading engine.
By what percentage did total population change between 2020 and 2024? Round to two decimal places.
| Species | 2020 | 2024 |
|---|---|---|
| Mule Deer | 499 | 634 |
| Red-tailed Hawk | 194 | 147 |
| Moose | 251 | 323 |
| Jackrabbit | 343 | 264 |
| Beaver | 391 | 468 |
| River Otter | 210 | 151 |
| Total individuals | 1,888 | 1,987 |
Reveal the marked answer and correction
The submitted answer
4.98%
Uses the ending total as the base.
The corrected answer
5.24%
Uses the starting total as the base.
(1,987 − 1,888) ÷ 1,888 × 100 = 5.24%
The change is 99 individuals. Measure it against the 1,888 you started with.
Carry this method: add the totals first, then divide the change by the starting total.
This illustrates one marked question. It is not a candidate result or a McKinsey score.