Question 13 • *Integrated Math II Full
First sort the 11 scores: 13, 15, 17, 18, 20, 20, 21, 22, 24, 25, 27. The original lower and upper quartiles are 17 and 24, so the interquartile range is 7; decreasing it by 1 means the new IQR must be 6. If she scores 23, the sorted list has 12 values, with Q1 = (17 + 18) ÷ 2 = 17.5 and Q3 = (23 + 24) ÷ 2 = 23.5, giving an IQR of 6. So she would need to score 23 points.
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