chocolatechip_543
The following table shows the probability distribution for a discrete random variable.
X 13 16 18 21 23 25 26 31
P(X) 0.07 0.21 0.17 0.25 0.05 0.04 0.13 0.08
The mean of the discrete random variable X is 20.59. What is the variance of X? Round your answer to the nearest hundredth.
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hal_stirrup
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\[s2 = Σ ( x _{I} - x )2 / ( n - 1 )\]
hal_stirrup
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are you there??
chocolatechip_543
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can you explain the equation a bit?
hal_stirrup
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sure lets star with \[\sum_{i=1}^{n}\]
hal_stirrup
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do you understand what this means?
hal_stirrup
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good then\[x_{i} -x\] xi is each value of your x value .
-x really i cant use xbar because the keyboard is limited .. x bar is the average= \[xbar=\sum_{i=1} x _{i}/n\]
hal_stirrup
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we are assuming that you have sample and not population as well !!!!
chocolatechip_543
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alright..I'm a little lost now
hal_stirrup
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tell me where.
chocolatechip_543
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at the last part you posted
hal_stirrup
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"we are assuming that you have sample and not population as well"
that
chocolatechip_543
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yes and before that
hal_stirrup
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look. inorder to help you you need to be clear as to where are you not understanding . so i can help you better. thanks
chocolatechip_543
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I'm sorry, I just don't understand it.
hal_stirrup
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no need to be sorry . :)
hal_stirrup
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have you done statistics before ?
chocolatechip_543
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no, but this is in my algebra 2 work
hal_stirrup
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thats cool/
hal_stirrup
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do you now how to get the mean?
hal_stirrup
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ok so were half way.
hal_stirrup
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lets talk concept first. is that ok?
hal_stirrup
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variance is the distance from the mean measured in squares. |dw:1343956195413:dw|
hal_stirrup
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in you r case you have many data points. so really your job is fine all the distance from the mean and then sum them up and divide by the number of data point and minus 1.
hal_stirrup
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s2=Σ(xI−x)2/(n−1) thats what this formula say.
chocolatechip_543
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oh alright
hal_stirrup
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share what your thinking if you like?
hal_stirrup
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if you like to , be my fan and send my question and thoughts if you want and dont forget to click on best response . thanks @chocolatechip_543