1. **State the problem:** We need to find the percentile rank of a score of 141 in a class of 20 students with the given scores. 2. **List the scores:** 168, 152, 112, 88, 95, 123, 177, 166, 145, 104, 112, 156, 110, 141, 177, 166, 134, 190, 111, 120. 3. **Sort the scores in ascending order:** 88, 95, 104, 110, 111, 112, 112, 120, 123, 134, 141, 145, 152, 156, 166, 166, 168, 177, 177, 190. 4. **Count the number of scores less than 141:** These are 88, 95, 104, 110, 111, 112, 112, 120, 123, 134, totaling 10 scores. 5. **Count the number of scores equal to 141:** There is 1 score equal to 141. 6. **Calculate the percentile rank using the formula:** $$\text{Percentile Rank} = \frac{\text{Number of scores less than } 141 + 0.5 \times \text{Number of scores equal to } 141}{\text{Total number of scores}} \times 100$$ 7. **Substitute the values:** $$\frac{10 + 0.5 \times 1}{20} \times 100 = \frac{10 + 0.5}{20} \times 100 = \frac{10.5}{20} \times 100 = 52.5$$ 8. **Round to the nearest percentile:** 53. **Final answer:** The percentile rank of a score of 141 is **53**.