1. **State the problem:** We have a list of midterm test scores and need to find the lowest score that is above the 80th percentile, which means the lowest score that is higher than 80% of all scores. 2. **List the scores:** 45, 95, 67, 50, 70, 81, 63, 83, 55, 72, 78, 62, 59, 74, 68, 70, 91, 75, 88, 68 3. **Sort the scores in ascending order:** $$45, 50, 55, 59, 62, 63, 67, 68, 68, 70, 70, 72, 74, 75, 78, 81, 83, 88, 91, 95$$ 4. **Find the position of the 80th percentile:** There are $n=20$ scores. The 80th percentile position is given by: $$P = 0.8 \times (n+1) = 0.8 \times 21 = 16.8$$ 5. **Interpret the position:** The 16.8th score lies between the 16th and 17th scores in the sorted list. The 16th score is 81 and the 17th score is 83. 6. **Calculate the 80th percentile value by interpolation:** $$80th\ percentile = 81 + 0.8 \times (83 - 81) = 81 + 0.8 \times 2 = 81 + 1.6 = 82.6$$ 7. **Determine the lowest score above the 80th percentile:** The lowest score greater than 82.6 is 83. **Final answer:** The lowest score to receive an A (above the 80th percentile) is **83**.