Given the following set of data, find the value that corresponds to the 75th percentile.
10, 44, 15, 23, 14, 18, 72, 56
2007-09-24 17:57:29 · 2 answers · asked by Splendidy 1 in Science & Mathematics ➔ Mathematics
Well, you're right that the 75th percentile would be the sixth item in a list of eight...but I'm pretty sure the list needs to be sorted. So first, rearrange those numbers.
10, 14, 15, 18, 23, 44, 56, 72
The 75th percentile is thus 44.
2007-09-24 18:06:14 · answer #1 · answered by Anonymous · 0⤊ 3⤋
18 looks closer to the 25th percentile than the 75th percentile. You find the mean and variance of the data. Then you estimate the "sigma" of the normal distribution as sqrt(variance/7). Now the computed mean becomes the best estimate of the mean of a normal distribution. You can go to the friendly Z distribution to find the 75th percentile as a function of sigma. Remember, the distribution goes from lowest to highest value. I suspect you did this backwards.
2007-09-24 18:06:46 · answer #2 · answered by cattbarf 7 · 0⤊ 3⤋