I have tried working out this question for a few days and I was wondering if anyone could help me answer it? I've asked several people for help yet I'm not getting the right answer.
A set of 15 numbers has mean 7 and standard deviation 4. A second set of 25 numbers has mean 9 and standard deviation 5. What is the standard deviation of the combined set of 40 numbers?
Give your answer to 3 s.f. if appropriate.
Mathematics stats question Watch
- Thread Starter
- 13-11-2016 18:42
- 13-11-2016 18:58