Aptitude Question ID : 93632

If p : q : r = 1 : 2 : 4, then $\sqrt{5p^{2}+q^{2}+r^{2}}$ is equal to :
[A]4r
[B]5p
[C]2q
[D]5

5p
$\because \frac{p}{1} = \frac{q}{2} = \frac{r}{4} = k (let)$
$=> p = k, q = 2k, r = 4k$
$\therefore \sqrt{5p^{2}+q^{2}+r^{2}} = \sqrt{5k^{2}+4k^{2}+16k^{2}}$
$=> \sqrt{25k^{2}}$
$=> 5k = 5p$
Hence option [B] is the right answer.