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hba
 2 years ago
Stats help required
hba
 2 years ago
Stats help required

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hba
 2 years ago
Best ResponseYou've already chosen the best response.0Actually i know. \[Mean=\sum_{}^{}fx/\sum_{}^{}f\] I know, \[\sum_{}^{}f=2000\]

sami21
 2 years ago
Best ResponseYou've already chosen the best response.0do you have the answer key is the answer 7.975 ???

hba
 2 years ago
Best ResponseYou've already chosen the best response.0I also think that is the answer as i tried doing it.

hba
 2 years ago
Best ResponseYou've already chosen the best response.0But here x1,x2,x3 cannot be 8.5,7.5 and 8 because it is actually the mean

wio
 2 years ago
Best ResponseYou've already chosen the best response.1Now suppose that we call \[ \sum fx \]The 'total'

wio
 2 years ago
Best ResponseYou've already chosen the best response.1We want the 'total' of each sub population.

wio
 2 years ago
Best ResponseYou've already chosen the best response.1To get the 'total' of the whole population.

wio
 2 years ago
Best ResponseYou've already chosen the best response.1From there we can find the mean of the whole population.

ParthKohli
 2 years ago
Best ResponseYou've already chosen the best response.0We know that the sum is \(700 \times 8.5 + 800 \times 7.5 + 500 \times 8\)

hba
 2 years ago
Best ResponseYou've already chosen the best response.0No No No 8.5,7.5 and 8 cannot be x

wio
 2 years ago
Best ResponseYou've already chosen the best response.1Yeah, but he's not using that formula.

ParthKohli
 2 years ago
Best ResponseYou've already chosen the best response.0Since mean is sum of observations divided by number of observations, we know that the sum of observations multiplied by the number of observations is the sum of observations.

wio
 2 years ago
Best ResponseYou've already chosen the best response.1He using this: \[ \sum fx = \frac{\sum fx}{\sum f}\times \sum f \]

ParthKohli
 2 years ago
Best ResponseYou've already chosen the best response.0Can you continue from this point?

sami21
 2 years ago
Best ResponseYou've already chosen the best response.0i don't think there is any problem with taking them as x's . what you alreadyy did is correct 7.975 .

hba
 2 years ago
Best ResponseYou've already chosen the best response.0But how can you say mean of x is actually x?

sami21
 2 years ago
Best ResponseYou've already chosen the best response.0(8.5*700 + 800*7.5 + 500*8)/2000

sami21
 2 years ago
Best ResponseYou've already chosen the best response.0these are different random variables for the whole population . you can just use them in the formula .

hba
 2 years ago
Best ResponseYou've already chosen the best response.0It says that it is the mean @sami21

wio
 2 years ago
Best ResponseYou've already chosen the best response.1Okay so if you have three means... suppose they are \(m_1, m_2, m_3\)

wio
 2 years ago
Best ResponseYou've already chosen the best response.1\[ m_1 = \frac{\sum_1fx}{\sum_1f} \]

sami21
 2 years ago
Best ResponseYou've already chosen the best response.0yes it does says . and requires the mean for population . which should be taking the means of the sub populatiions .

hba
 2 years ago
Best ResponseYou've already chosen the best response.0One more thing,If that is not the formula,What is it?

wio
 2 years ago
Best ResponseYou've already chosen the best response.1the mean of all three will be: \[ m_4 = \frac{\sum_4 fx}{\sum_4x} = \frac{\sum_1 fx + \sum_2 fx+ \sum_3 fx}{\sum_1 f + \sum_2 f + \sum_3 f} \]

wio
 2 years ago
Best ResponseYou've already chosen the best response.1This is because the total frequency \(\sum_4 f\) is the sum of the sub frequencies. The total weight \(\sum_4 fx\) is equal to the sum of all the weights.

wio
 2 years ago
Best ResponseYou've already chosen the best response.1Notice how \[ m_1 = \frac{\sum_1 fx}{\sum_1 f} \implies m_1\sum_1 f = \sum_1 f x \]

hba
 2 years ago
Best ResponseYou've already chosen the best response.0Okay so what would the formula basically?

wio
 2 years ago
Best ResponseYou've already chosen the best response.1Given means... \(m_1, m_2, \dots \) with total frequencies \(f_1,f_2,...\) then the mean of the totals is: \[ \frac{\sum m_if_i}{\sum f_i} \]

wio
 2 years ago
Best ResponseYou've already chosen the best response.1It's not the same formula, they just happen to be the same though by coincidence.
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