Description
The serum cholesterol levels (in mg/dL) of 20 individuals
are
203 , 259 , 220 ,
252 , 191 , 257 ,
249 , 242 , 237 ,
213 , 186 , 198 ,
235 , 211 , 254 ,
225 , 208 , 189 ,
244 , 228
Find 25th and 80th percentiles for these cholesterol levels.
The 25th percentile____mg/dl
The 80th percentile____mg/ld
Explanation & Answer
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First of all arranging the data from least to greatest
186,189,191,198,203,208,211,213,220,225,228,235,237,242,244,249,252,254,257,259
Now for the 25 th percentile multiply the total data with the .25=.25*20=5,so it is the average of 5 th and 6 th data =205.5mg/dl
For the 80th percentile multiply the number 20 with .8=20*.8=16 th average of 16 and 17 th data =249+252/2 =250.5 mg/dl