Adam E.
asked • 05/19/19Sample Variance Question
Hi, I am reading a book for a hobby that has a math calculation I don't understand. I haven't been in school in 10 years.
The book reads: Now record the variation from the average of the seven samples, which is +2.572 and -4.428 weeks. Average these limits to obtain t3.5 weeks.
The sample included the numbers: 23,9,21,12,22,24,17
Can someone tell me how the limits were obtained and what type of calculators I could use to perform these calculations myself?
Thanks!
More
1 Expert Answer
The Average or Mean of the sample equals (9 + 12 + 17 + 21 + 22 + 23 +24) ÷ 7 or 128/7.
Variance for the 7 Data Points in the sample is given by:
[(9 − 128/7)2 + (12 − 128/7)2 + (17 − 128/7)2 + (21 − 128/7)2 + (22 − 128/7)2 + (23 − 128/7)2 + (24 − 128/7)2] ÷ (7 − 1) which simplifies to 33.90476191.
Note that, if the given 7 Data Points were an entire population instead of a sample of an entire population, then the Variance would be given by:
[(9 − 128/7)2 + (12 − 128/7)2 + (17 − 128/7)2 + (21 − 128/7)2 + (22 − 128/7)2 + (23 − 128/7)2 + (24 − 128/7)2] ÷ (7 − 0) which simplifies to 29.06122449.
Still looking for help? Get the right answer, fast.
Ask a question for free
Get a free answer to a quick problem.
Most questions answered within 4 hours.
OR
Find an Online Tutor Now
Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.
Jim S.
Adam, Need more information about the problem. The mean(average) of the sample is 18.29. If you record the variation from the average you will get 7 numbers none of which are 2.572 and -4.428 ????05/19/19