Results 1 to 7 of 7

Thread: Question about standard deviations? (yeah... maths :( - v quick!)

  1. #1
    Senior Member
    Join Date
    Jun 2005
    Location
    London
    Posts
    623
    Thanks
    3
    Thanked
    1 time in 1 post

    Question about standard deviations? (yeah... maths :( - v quick!)

    I am really confused, please could somebody enlighten me!

    A bottle has mean mass 3kg and standard deviation 0.05kg. What are the mean and standard deviation of 12 bottles?

    well mean is 36kg, but I can't for the life of me remember or find out how to do standard deviation of 12 things. Please somebody!

    Thank you!

    ShMeE
    Current: Shuttle SX58J3, i7 950, Corsair 16GB, 2x 1.5TB, XFX 6850 1GB, 3x Samsung 23" 1920x1080, 5760x1080 = AWESOME!

    Laptop: Vaio Z (13.3")
    Hexus Trust ¦ Shmee150.co.uk (Supercar Blog)

  2. #2
    Ah, Mrs. Peel! mike_w's Avatar
    Join Date
    Oct 2003
    Location
    Hertfordshire, England
    Posts
    3,326
    Thanks
    3
    Thanked
    9 times in 7 posts
    Standard deviation (if memory serves) is:

    For each value, do the value take away the mean. Square the result, and then add them all up, and divide by the number of values. Find the square root of all of that.

    I think.
    "Well, there was your Uncle Tiberius who died wrapped in cabbage leaves but we assumed that was a freak accident."

  3. #3
    Senior Member
    Join Date
    Jun 2005
    Location
    London
    Posts
    623
    Thanks
    3
    Thanked
    1 time in 1 post
    I think that's more variance basedm and I'm after something that you do involving 12 and 0.05 and 3, and the answer is 0.173, but I really can't see how to get there.

    Anybody else have an idea?

    Thanks,

    ShMeE
    Current: Shuttle SX58J3, i7 950, Corsair 16GB, 2x 1.5TB, XFX 6850 1GB, 3x Samsung 23" 1920x1080, 5760x1080 = AWESOME!

    Laptop: Vaio Z (13.3")
    Hexus Trust ¦ Shmee150.co.uk (Supercar Blog)

  4. #4
    Senior Member
    Join Date
    Jul 2003
    Location
    London
    Posts
    888
    Thanks
    9
    Thanked
    4 times in 4 posts
    square your original standard deviation to get the variance

    multiply by 12

    square root for your new standard deviation

  5. #5
    Senior Member
    Join Date
    Jun 2005
    Location
    London
    Posts
    623
    Thanks
    3
    Thanked
    1 time in 1 post
    Yey!!!!

    Thank you very much

    ShMeE
    Current: Shuttle SX58J3, i7 950, Corsair 16GB, 2x 1.5TB, XFX 6850 1GB, 3x Samsung 23" 1920x1080, 5760x1080 = AWESOME!

    Laptop: Vaio Z (13.3")
    Hexus Trust ¦ Shmee150.co.uk (Supercar Blog)

  6. #6
    Ah, Mrs. Peel! mike_w's Avatar
    Join Date
    Oct 2003
    Location
    Hertfordshire, England
    Posts
    3,326
    Thanks
    3
    Thanked
    9 times in 7 posts
    What exactly is the question?
    "Well, there was your Uncle Tiberius who died wrapped in cabbage leaves but we assumed that was a freak accident."

  7. #7
    Senior Member
    Join Date
    Jun 2005
    Location
    London
    Posts
    623
    Thanks
    3
    Thanked
    1 time in 1 post
    The weights of bottles of wine are normally distributed with mean weight 3kg and standard deviation 0.05kg. Find the mean and standard deviation of 12 bottles of wine.

    It's about the first question in S3, but it's been a long summer and I can't remember much of what happened in S2

    ShMeE
    Current: Shuttle SX58J3, i7 950, Corsair 16GB, 2x 1.5TB, XFX 6850 1GB, 3x Samsung 23" 1920x1080, 5760x1080 = AWESOME!

    Laptop: Vaio Z (13.3")
    Hexus Trust ¦ Shmee150.co.uk (Supercar Blog)

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Just a quick question - Hard Drive
    By Crazy Fool in forum PC Hardware and Components
    Replies: 2
    Last Post: 13-09-2005, 03:20 PM
  2. Quick Question: PSU's with 1x120mm fan question
    By philyau in forum PC Hardware and Components
    Replies: 10
    Last Post: 05-09-2005, 02:30 PM
  3. Quick Linux question from a newbie...
    By madmonkey in forum Software
    Replies: 19
    Last Post: 26-08-2005, 09:07 PM
  4. quick maths question
    By Nick F in forum General Discussion
    Replies: 15
    Last Post: 07-06-2005, 03:07 PM
  5. Skii's Aircraft Quiz
    By Skii in forum PC
    Replies: 60
    Last Post: 04-12-2003, 06:34 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •