- This topic has 11 replies, 5 voices, and was last updated 11 years ago by John Moffat.
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- October 31, 2012 at 12:07 pm #54954
Hi John,
Can you explain something to me please?
A 95% confidence level produces a 1.65 normal distribution value.
I can’t understand how this value is produced. I know this means a 5% probability level but not how I extract the -1.65 value from the distribution table!!!Help please?????
October 31, 2012 at 3:28 pm #106240Hi harri!
95% means 0.95, we must have arrived at 0.95 by adding “some value” to 0.5 (since d1 > 0). If we calculate that “value” by subtracting 0.5 from 0.95, we will have 0.45. Now just go to the Normal distribution table and see the corresponding value of 0.45, you’ll get 1.65.
Hope john likes it π
October 31, 2012 at 6:28 pm #106241Hi muhaimin,
Thanks for your response but if I look up 0.45 I get 0.1736?
I’m confused. Am I not using the table correctly?
October 31, 2012 at 6:38 pm #106242Do I find 0.4505 and that is equal to 1.65?
I think so!November 1, 2012 at 7:11 am #106243yes harri, closer to 0.45 is 0.4505 and 0.4495, so it can either be 1.65 or 1.64.
Since the examiner rounds it to the lower side so do we.
November 1, 2012 at 2:56 pm #106244Thanks Muhaimin, you helped solve my headache!
Much appreciatedNovember 1, 2012 at 3:55 pm #106245most welcome!
November 1, 2012 at 5:12 pm #106246Good answer Muhalmin.
(Some of the exam/revision kits try to be clever and start approximating the tables, but there is no need to in the exam!)November 4, 2012 at 2:32 pm #106247Thanks john, I would be pleased to help the other students as well if i get the opportunity to do so.
I would appreciate if you see my post (a question from pilot paper) which is still unanswered. I know your answer would be “Time constraints! time constraints! ;)” ….
Dear Harripool! if you can help me out? π
ThanksNovember 10, 2012 at 9:27 am #106248at 90% confidence level, is the value from the table 1,29???
November 10, 2012 at 9:36 am #106249You should find 0.9-0.5=0.40 (cell), then you roughly get 1.285.
November 10, 2012 at 9:29 pm #106250correct π
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