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-   -   Sample mean (https://www.askmehelpdesk.com/showthread.php?t=409677)

  • Oct 26, 2009, 12:52 AM
    umadevi S
    Sample mean
    Two laboratories A and B carry out independent estimates of fat content in ice cream made by a firm. A sample taken from each batch gives the following fat content:

    Batch No - 1 2 3 4 5 6 7 8 9 10
    Lab A _ 7 8 7 3 8 6 9 4 7 8
    Lab B _ 9 8 8 4 7 7 9 6 6 6

    Is there a significant difference between the mean fat-content obtained by the two laboratories A and B?
  • Oct 26, 2009, 10:18 AM
    Nhatkiem

    The mean of any sample is



    Find the mean for both samples and take the difference.
  • Oct 26, 2009, 11:19 PM
    Unknown008

    Hm, by the way Nhatkiem, the code for 'space' is '\,' [backslash comma]
  • Oct 26, 2009, 11:24 PM
    morgaine300

    Or just backslash and a space.
  • Oct 26, 2009, 11:26 PM
    Unknown008
    Oh, yes, you're right :o Less to type
  • Oct 26, 2009, 11:29 PM
    morgaine300

    Yes, and I'm bound to take the easy way out. LOL.
  • Oct 27, 2009, 12:07 AM
    Nhatkiem

    Oh really.. lol I was getting annoyed at the spaces not entering.. so.. periods haha
  • Oct 27, 2009, 08:23 AM
    Chris-infj
    Quote:

    Originally Posted by umadevi S View Post
    Two laboratories A and B carry out independent estimates of fat content in ice cream made by a firm. A sample taken from each batch gives the following fat content:

    Batch No - 1 2 3 4 5 6 7 8 9 10
    Lab A _ 7 8 7 3 8 6 9 4 7 8
    Lab B _ 9 8 8 4 7 7 9 6 6 6

    Is there a significant difference between the mean fat-content obtained by the two laboratories A and B?

    You need to calculate the mean for sample A and also the standard deviation for sample A.
    Then, also the mean for sample B and the standard deviation for sample B. Look up the formulae in your textbook. The mean for sample A should differ from that of sample B. But the question is 'IS that difference SIGNIFICANT?' or can it just be attributed to 'normal' variability in the data.

    Then look up hypothesis testing: difference between two means in your textbook or elsewhere and follow the procedure for hypothesis testing.

    You'll have to decide on the level of significance of the test if none is given. Typically, use a 5% level of significance.

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