标题: sampling and estimation [打印本页] 作者: Flok 时间: 2011-9-25 02:24 标题: sampling and estimation
curriculum june 2012
quantitative methods,
reading 10 sampling and estimation,
page 580 of curriculum
im unable to comprehend practice problem no.10 . if anyone could possibly explain the solution...
thank you作者: Zestt 时间: 2011-9-25 02:35
I've curriculum June 2011 . Please mention the question here, it would be easier to answer....作者: yodacaia 时间: 2011-9-25 02:45
an exchange rate has a given expected future value and standard deviation.
A. assuming that the exchange rate is normally distributed, what are the probabilities that the exchange rate will be at least 2 or 3 standard deviations away from its mean?
B part is about chebyshev's inequality. but im sure, if any one could possibly explain the A part, i will get the B.
thank you作者: zbird2134 时间: 2011-9-25 02:56
The Z table values for "2" and "3" under the zero column are 0.9772 and 0.9987. Since this question is asking about "at least" 2 or 3 standard deviations, you're looking for the area under the tails on either side of the mean. Which means one minus the area under the curve, times two.
So for 2 standard deviations, the area under the curve based on the Z table value is 0.9772. Which implies area under the tail is (1 - 0.9772) = 0.0228. Ultimately, area under the both the tails, because the normal distribution is symmetrical, is (2 * 0.0228) = 0.0456.
Hope this helps.作者: Rasec 时间: 2011-9-25 03:06
thank you oyster, you are awesome. now it makes perfect sense...
thank you belaal for directing me how to ask the question...
