Puzzling HP49G+ SDEVfunction Message #1 Posted by KarlLudwig Butte on 26 Mar 2006, 7:03 a.m.
Hello All,
I have a difficult question about the SDEV function of the HP49G+ which puzzles me: There are 4 figures for which I would like to calculate the standard deviation:
6.5
12.1
5.4
10.3
I've read this excercise in a financial mathematic text book and the author is calculating the standard deviation as follows:
SDEV = SQRT(1/4*(SQR(6.53.4)+SQR(12.13.4)+SQR(5.43.4)+SQR(10.33.4))
SDEV = 8.3
When entered into the HP49G+ and using the formula above the same result is displayed. But using the predefined function Mean and SDEV the 49 displays:
Mean: 3.4250
SDEV: 9.6088
First I thought it maybe because in the textbook the 3rd and 4th decimal isn't used so I recalculated with 3.4250 instead of 3.4 but in vain. Tries with an HP49G, HP48G and HP41 the same differences in results were displayed. So it doesn't seem to be a bug of the HP49G+ Firmware (Version: HP49B Rev.: 2.012).
Has anyone of you a hint where the difference comes from ? Thank you very much in advance.
Has anyone
