Solve the Problem $19.6 \mathrm {~m} / \mathrm { sec }$

Solve the problem.
-A stone thrown downward with an initial velocity of $19.6 \mathrm {~m} / \mathrm { sec }$ will travel a distance of $s$ meters, where $\mathrm { s } ( \mathrm { t } ) = 4.9 \mathrm { t } ^ { 2 } + 19.6 \mathrm { t }$ and $\mathrm { t }$ is in seconds. If a stone is thrown downward at $19.6 \mathrm {~m} / \mathrm { sec }$ from a height of $294 \mathrm {~m}$ , how long will it take the stone to hit the ground? Round your answer to the nearest second.

A) $16 \mathrm { sec }$
B) $4 \mathrm { sec }$
C) $6 \mathrm { sec }$
D) $10 \mathrm { sec }$