Final answer:
To find Lucy's three test scores, we use the given information about the median, mean, and range. Lucy's three test scores are 73, 86, and 102.
Step-by-step explanation:
To find Lucy's three test scores, we need to use the given information about the median, mean, and range.
The median score is 86, which means that one of the test scores is 86.
The mean score is 87, which is the sum of all three test scores divided by 3. Multiply the mean score by 3 (87 x 3 = 261) and subtract the sum of the other two test scores from it (261 - 86 = 175). This gives us the sum of the remaining two test scores.
The range is 13, which is the difference between the highest and lowest test scores. Since 86 is the lowest test score, subtract the range from it (86 - 13 = 73) to find the highest test score. Then, subtract the highest test score from the sum of the remaining two test scores to find the middle test score (175 - 73 = 102).
Therefore, Lucy's three test scores are 73, 86, and 102.