Question 1045405
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A set X with n(x)=525 is partitioned into subsets X_1, X_2, X_3, X_4, X_5, X_6. 
If n(X_1)=n(X_2)=n(X_3), n(X_4)=n(X_5)=n(X_6) and n(X_1)=6n(X_4), find n(X_1)
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Let n(X_4) = n for brevity.


Then n(X_1) = n(X_2) = n(X_3) = 6n,

     n(X_4) = n(X_5) = n(X_6) =  n.

Hence, you have an equation

3n + 3*(6n) = 525,   or

21n = 525.

It implies n = {{{525/21}}} = 25.

Then n(X_1) = 6n = 150.

<U>Answer</U>.  n(X_1) = 150.
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