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Median
Message posted by Ally on September 20, 1999 at 12:00 AM (ET)
I need to find the Median of this group:
Class Frequency
89.5-94.5 5
94.5-99.5 10
99.5-104.5 14
104.5-109.5 13
109.5-114.5 15
114.5-119.5 21
119.5-124.5 16
124.5-129.5 7
129.5-134.5 2
I am havign a difficult time finding the median of this group of numbers...
I need some help on figuring this out!!!
READERS RESPOND:
(In chronological order. Most recent at the bottom.)
Re: Median
Message posted by JG on September 21, 1999 at 12:00 AM (ET)
You need the frequencies to calculate the median for grouped data by means of a simple formula.
Re: Median
Message posted by JG on September 21, 1999 at 12:00 AM (ET)
I just notice that you do have the frequencie, so that the median for grouped data is 109.5 + 5(10.5/15) = 113.0
Re: Median
Message posted by Jay on October 4, 1999 at 12:00 AM (ET)
Median is the middle(ith) value. You have 103 values. 103/2=52.5. Use the 52nd or 53rd value. Both of these numbers fall in one group. That's your median.
Re: Median
Message posted by Glen Koorey on October 5, 1999 at 12:00 AM (ET)
Actually your middle value is the 52nd value of 103, which is in the "109.5-114.5" group of 15 values.
Because your values are grouped into intervals of five (with no indication of actual values), a simple assumption is to assume that the values are evenly spread across the whole range. So your 15 values are evenly spread between 109.5 and 114.5 (i.e. 0.333 apart with 0.167 at each end).
The median value is the 10th of these values = 109.5 + 0.167 + 5*(10-1)/15 = 112.667
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