1. The greatest possible percentage increase in a test score happens when both "bonus" questions were on it - which is an increase of 4 points. Let's calculate it for all 5 of Amy's test scores.
- Test 1: \(\frac{(4 + 20 + 40 + 30) - (20 + 40 + 30)}{20 + 40 + 30} * 100\% \approx 4.44\%\).
- Test 2: \(\frac{(4 + 6 + 40 + 28) - (6 + 40 + 28)}{6 + 40 + 28} * 100\% \approx 5.41\%\).
- Test 3: \(\frac{(4 + 10 + 42 + 36) - (10 + 42 + 36)}{10 + 42 + 36} * 100\% \approx 4.55\%\).
- Test 4: \(\frac{(4 + 22 + 20 + 22) - (22 + 20 + 22)}{22 + 20 + 22} * 100\% = 6.25\%\).
- Test 5: \(\frac{(4 + 20 + 26 + 34) - (20 + 26 + 34)}{20 + 26 + 34} * 100\% = 5\%\).
Test 4 has the greatest possible percentage increase.
2. The least possible percentage increase in a test score happens when no "bonus" questions were on it - which is a change of 0 points. It doesn't matter for which test this happens to, as the change will still be 0%.
3. We are asked to find the difference between these values, which is 6.25% - 0% =
6.25%.