# GRE quiz (interquartile range (IQR)) problem

I’m confused how Q1 median is 11

How I solved my part for Q1 median:
For interquartile range (IQR) part…
Q1 med(8,9,11,16,16) = 60 then divided by 5 = 12

Did I do math wrong? If so, can someone help me clarify it? Please?

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Hi @Polancas, welcome to Achievable, and thanks for posting!

Your math is almost correct. The difference is that you’re calculating the mean, but for IQR you need to calculate the median.

Mean is the typical “average” we talk about: the sum of the value divided by the number of values. It’s as you did the math: mean = (8 + 9 +11 +16 +16)/5 = 60/5 = 12

Median is the middle-most value. Since it’s already sorted, we can just pick the middle one: median = (8,9, 11,16,16) = 11.

For median, if it is a set with an even amount of numbers, you take the mean of the middle-most two values: median = (8,9,16,16) = (9+16)/2 = 12.5

Hope this helps! Please let me know if I can explain further or if there are other topics I can clarify.

Oh okay, that makes sense! Thank you!

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