• Apr 5th 2009, 03:19 PM
ASDF1
How do I add 3 mean numbers with different standard deviations?

Mean: 642 SD: 24
475 SD: 12
265 SD: 26

I have like 5 different problems that are similar, so instead of an answer, if you can show me how to do it, that would be wonderful. Thanks in advance.
• Apr 5th 2009, 04:18 PM
mr fantastic
Quote:

Originally Posted by ASDF1
How do I add 3 mean numbers with different standard deviations?

Mean: 642 SD: 24
475 SD: 12
265 SD: 26

I have like 5 different problems that are similar, so instead of an answer, if you can show me how to do it, that would be wonderful. Thanks in advance.

Please state the question exactly as it's written in your book (or wherever it's come from).
• Apr 5th 2009, 04:49 PM
ASDF1
Assuming their scores are independent, what is the team's score and standard deviation?
• Apr 6th 2009, 03:16 PM
mr fantastic
Quote:

Originally Posted by ASDF1
Assuming their scores are independent, what is the team's score and standard deviation?

Is that the whole question? I don't see how to do it without more information.
• Apr 7th 2009, 05:34 AM
aidan
Quote:

Originally Posted by ASDF1
How do I add 3 mean numbers with different standard deviations?

Mean: 642 SD: 24
475 SD: 12
265 SD: 26

I have like 5 different problems that are similar, so instead of an answer, if you can show me how to do it, that would be wonderful. Thanks in advance.

With out knowing what you are attempting
642 + 475 + 265 = 1382

However, to manipulate the mean it seems as if you must also know the 'n' or number of values to calculate the mean and standard deviation.