1. **Problem statement:** Given mock and final GCSE exam percentages for five subjects, analyze the differences and averages. 2. **List given data:** - Maths: Mock = 45, Final = 68 - English: Mock = 50, Final = 80 - Geography: Mock = 73, Final = 82 - Physics: Mock = 55, Final = 70 - Chemistry: Mock = 64, Final = 72 3. **Calculate if final English GCSE exam score was 60% better than mock:** A 60% improvement means: $$\text{Final}_\text{English} = \text{Mock}_\text{English} + 0.60 \times \text{Mock}_\text{English} = 1.60 \times 50 = 80$$ This matches the given final score, confirming the statement. 4. **Calculate average mock scores:** $$\text{Average mock} = \frac{45 + 50 + 73 + 55 + 64}{5} = \frac{287}{5} = 57.4$$ Since 57.4 is greater than 55, the statement about mock average score is true. 5. **Best predictor check for Chemistry:** Calculate percentage increase from mock to final for each subject: - Maths: $\frac{68 - 45}{45} \times 100 = 51.11\%$ - English: $\frac{80 - 50}{50} \times 100 = 60\%$ - Geography: $\frac{82 - 73}{73} \times 100 \approx 12.33\%$ - Physics: $\frac{70 - 55}{55} \times 100 \approx 27.27\%$ - Chemistry: $\frac{72 - 64}{64} \times 100 = 12.5\%$ Chemistry had the smallest relative increase, indicating the mock result was the best predictor of the final result. **Final Answers:** - The final English exam score was indeed 60% better than the mock. - The average mock score is $57.4 > 55$. - Chemistry mock exam was the best predictor of final results because it had the smallest percentage increase.