<span>98, 78 , 84, 75, 91
</span>
The interquartile range formula is the first <span>quartile </span>subtracted from the third quartile:
<span>IQR = Q3 – Q1.</span>
<span><span>****************************************************
Step 1: Put the numbers in order.
75, 78, 84, 91, 98
</span><span><span>Step 2: </span><span>Find the median</span>.
</span></span>75, 78,
84, 91, 98
<span>
<span><span>Step 3: </span><span>Place parentheses around the numbers above and below the median. </span>
Not necessary statistically, but it makes Q1 and Q3 easier to spot.
</span></span>(75, 78), 84, (91, 98)
<span>
<span><span>Step 4: </span>Find Q1 and Q3
Think of Q1 as a median in the lower half of the data and think of Q3 as a median for the upper half of data.
</span></span>(75, 78), 84, (91, 98)
<span>*(75, 78) ---> (75 + 78) </span>÷ 2 = 76.5
<span>*(91, 98) ---> (91 + 98) </span>÷ 2 = 94.5
<span>
<span><span>Step 5: </span>Subtract Q1 from Q3 to find the interquartile range.
94.5 – 76.5 = 18
IQR = 18</span></span>
