Share price volatility - Standard deviation issue task 39

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andydscott     2016-09-27 15:27:05

Raised this previously in another topic but realised it is probably best to start a new one.

I am strugglng with this one. I always get a few where my calculations say the standard deviation is less then 2 but the checker says they are good (ie > 2) I may well have made a mistake in my code, but even when I check the data in Excel I still get SD less than 2. data looks like this:

21
FANT 67 66 64 62 65 62 65 62 63 63 66 66 69 69
WOWY 98 97 97 98 98 100 97 99 95 97 99 103 99 99
VDKL 62 61 64 65 64 64 61 59 63 60 62 61 65 61
INSX 24 25 24 23 23 22 23 23 22 23 24 25 25 25
OBAM 107 106 107 106 106 107 107 106 105 104 103 103 103 104
MARU 75 71 68 71 70 69 72 70 66 64 67 66 70 68
SUGR 20 20 23 20 20 17 16 17 19 16 15 14 14 12
FOTA 47 48 49 48 47 48 47 48 47 46 45 46 46 45
GEEK 57 56 54 57 54 57 60 60 59 58 60 62 64 62
CKCL 236 237 238 238 239 240 240 241 241 240 239 238 239 239
DALG 25 23 24 24 26 23 26 26 28 30 31 33 33 34
YUKA 23 21 20 22 20 22 24 23 21 22 23 24 26 26
FLNT 21 25 23 25 24 21 21 17 21 25 27 30 28 25
BLEP 23 23 23 24 25 25 26 26 25 25 24 24 25 24
JABA 128 127 127 127 126 126 126 127 127 127 126 126 127 127
GOLD 81 79 79 77 78 79 80 81 80 80 82 83 82 81
JOOG 75 75 75 75 75 76 75 75 74 73 72 73 73 72
JEOP 62 61 61 59 61 62 62 63 62 64 66 68 66 68
MYTH 83 82 79 81 84 83 86 83 80 80 78 76 73 76
PNSN 23 21 19 16 18 18 21 23 23 20 21 21 24 27
ASDF 27 24 22 26 24 23 23 24 26 27 27 25 29 33

My solution looks like this:

SUGR GEEK DALG FLNT JEOP MYTH PNSN ASDF

Expected solution:

INSX SUGR GEEK DALG YUKA FLNT BLEP JEOP MYTH PNSN ASDF

So I am missing INSX, YUKA and BLEP

my calculations were:

INSX mean= 23.6428571429 sd= 1.04246567995  comm= 0.236428571429
YUKA mean= 22.6428571429 sd= 1.83642287603  comm= 0.226428571429
BLEP mean= 24.4285714286 sd= 0.979379228629 comm= 0.244285714286

sd definitely less than 2.

Even when I feed the data into Excel I still get the same numbers for standard deviation.

insx    24  25  24  23  23  22  23  23  22  23  24  25  25  25  1.04246568
yuka    23  21  20  22  20  22  24  23  21  22  23  24  26  26  1.836422876
blep    23  23  23  24  25  25  26  26  25  25  24  24  25  24  0.979379229

Have I gone wrong with my calculation of Standard Deviation? Have I misunderstod the problem or is the checker wrong?

I can't make this private since I haven't solved the problem, so I won't inlude my code unless requested.

andydscott     2016-09-27 18:42:27

Now sorted by quandry. I misunderstood instructions thinking I needed sd > 2.

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