If ( x ) varies inversely as ( left(y^{2}-1right) ) and is equal to 24 when ( y=10 ), then the value of ( x ) when ( y=5 ) is:
( (A) 99 )
(B) 12
(C) 24
(D) 100

( frac{x}{y^{2}-1} Rightarrow x=frac{k}{y^{2}-1} )
Put ( x=24, y=10 )
( 24=frac{k}{100-1}=frac{k}{99} )
( x=24 times 99 )
Put ( y=5 )
( x=frac{k}{25-1}=frac{24 times 99}{24}=99 . quad )

Option (A)