Statistics: Confidence Intervals question

[From: ] [author: ] [Date: 12-04-09] [Hit: ]

I dont understand how to do this at all.If someone could explain it, that would be great.Ive tried looking it up but cant find anything for finding a from b or vice versa.So, lets try it in your problem .......

In order to find a 86% confidence interval we need to find values a and b such that for Z∼N(μ=0,σ=1),
P(a
(a) Suppose a=−2.3506. Then b=

I don't understand how to do this at all. If someone could explain it, that would be great. I've tried looking it up but can't find anything for finding a from b or vice versa.

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lizzzardbreath -

Here is an important identity to remember:

P(a
So, let's try it in your problem ...

P(-2.3506 < Z
P(Z < b) = P(Z < -2.3506) + 0.86 = 0.00937 + 0.86 = 0.86937, so now we know ...

P(Z < b) = 0.86937, using a calculator (InvNorm) or interpolating in the Standard Normal table ...

b = 1.123418

Hope that helped

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keywords: Confidence,question,Intervals,Statistics,Statistics: Confidence Intervals question

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