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

sami21Best ResponseYou've already chosen the best response.0
do you have the answer key is the answer 7.975 ???
 one year ago

hbaBest ResponseYou've already chosen the best response.0
I also think that is the answer as i tried doing it.
 one year ago

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

wioBest ResponseYou've already chosen the best response.1
Now suppose that we call \[ \sum fx \]The 'total'
 one year ago

wioBest ResponseYou've already chosen the best response.1
We want the 'total' of each sub population.
 one year ago

wioBest ResponseYou've already chosen the best response.1
To get the 'total' of the whole population.
 one year ago

wioBest ResponseYou've already chosen the best response.1
From there we can find the mean of the whole population.
 one year ago

ParthKohliBest ResponseYou've already chosen the best response.0
We know that the sum is \(700 \times 8.5 + 800 \times 7.5 + 500 \times 8\)
 one year ago

hbaBest ResponseYou've already chosen the best response.0
No No No 8.5,7.5 and 8 cannot be x
 one year ago

wioBest ResponseYou've already chosen the best response.1
Yeah, but he's not using that formula.
 one year ago

ParthKohliBest ResponseYou've already chosen the best response.0
Since 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.
 one year ago

wioBest ResponseYou've already chosen the best response.1
He using this: \[ \sum fx = \frac{\sum fx}{\sum f}\times \sum f \]
 one year ago

ParthKohliBest ResponseYou've already chosen the best response.0
Can you continue from this point?
 one year ago

sami21Best ResponseYou've already chosen the best response.0
i don't think there is any problem with taking them as x's . what you alreadyy did is correct 7.975 .
 one year ago

hbaBest ResponseYou've already chosen the best response.0
But how can you say mean of x is actually x?
 one year ago

sami21Best ResponseYou've already chosen the best response.0
(8.5*700 + 800*7.5 + 500*8)/2000
 one year ago

sami21Best ResponseYou've already chosen the best response.0
these are different random variables for the whole population . you can just use them in the formula .
 one year ago

hbaBest ResponseYou've already chosen the best response.0
It says that it is the mean @sami21
 one year ago

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

wioBest ResponseYou've already chosen the best response.1
\[ m_1 = \frac{\sum_1fx}{\sum_1f} \]
 one year ago

sami21Best ResponseYou've already chosen the best response.0
yes it does says . and requires the mean for population . which should be taking the means of the sub populatiions .
 one year ago

hbaBest ResponseYou've already chosen the best response.0
One more thing,If that is not the formula,What is it?
 one year ago

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

wioBest ResponseYou've already chosen the best response.1
This 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.
 one year ago

wioBest ResponseYou've already chosen the best response.1
Notice how \[ m_1 = \frac{\sum_1 fx}{\sum_1 f} \implies m_1\sum_1 f = \sum_1 f x \]
 one year ago

hbaBest ResponseYou've already chosen the best response.0
Okay so what would the formula basically?
 one year ago

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

wioBest ResponseYou've already chosen the best response.1
It's not the same formula, they just happen to be the same though by coincidence.
 one year ago
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