A) 8
B) 9
C) 10
D) 5
Correct Answer: B
Solution :
\[\frac{n-r+1}{r}=\frac{84}{36}=\frac{7}{3}\] and \[\frac{n-r}{r+1}=\frac{126}{84}=\frac{3}{2}\] \[\therefore \]\[\frac{7}{3}r-1=n-r=\frac{3}{2}(r+1)\] or \[14r-6=9r+9\] or \[r=3\]. So, \[n=9\].You need to login to perform this action.
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