GRE quant problems inter-quartile range for 2 or 3 numbers

GRE Quant Problem Solving
1

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Hi, I am having some confusion in calculating interquartile range for a list containing 2 and 3 values.

1,2 - Range is 2-1=1. But what is Q1 and Q2? Median will be 1.5, Q1 will be (1+1.5)/2 and Q2 will be (1.5+2)/2. So interquartile range will be 0.5

Similarly, 1,2,3- Median is 2, Range is 3-1=2, Q1 is (1+2)/2 and Q3 is (2+3)/2 so inter-quartile range is 1.

Is this correct?

2

Q_1 = 1, Q_2 = 1.5, and Q_3 = 2. Thus, the \operatorname{IQR} = Q_3 - Q_1 = 2 = \operatorname{Range}

The method you used to calculate Q_1 and Q_3 is different from the one the GRE uses.