This is a statistics question involving Z Scores. I know it has to be between 25% and 75%. Can someone explain how to "unnormalize" this?
2006-06-19 15:55:19 · 3 answers · asked by David M 2 in Science & Mathematics ➔ Mathematics
On the normal table, the z score such that 75% is to the left is 0.67. That means that the 75th percentile is 0.67 SD's above the mean. Since the normal is symmetric, the 25th percentile is 0.67 SD's below the mean. So, to get the middle 50%, add and subtract .67*10 = 6.7 from 30. The range is 23.3 and 36.7. This is assuming that the population is normal.
2006-06-19 16:09:59 · answer #1 · answered by blahb31 6 · 1⤊ 0⤋
The middle 50% of a normally-distributed set of data are bounded by z-scores of -0.67 and 0.67. For your data set, the bounds are approximately 23.3 and 36.7.
2006-06-19 16:17:19 · answer #2 · answered by jimbob 6 · 0⤊ 0⤋
23.2551 to 36.7449
invnorm(0.75,30,10) gives the upper limit
then just subtract the mean from the uperlimit, and subtract your answer from the mean
2006-06-19 16:04:00 · answer #3 · answered by Mathemagician 1 · 0⤊ 0⤋