Answer
$\frac{8}{7}$
Work Step by Step
Let $sin^{-1}\frac{1}{4}=y$, we have $sin(y)=\frac{1}{4},$ and
$sec(2sin^{-1}\frac{1}{4})=sec(2y)
=\frac{1}{cos(2y)}=\frac{1}{1-2sin^2y}=\frac{1}{1-2/16}=\frac{8}{7}$
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