$(11\%)$ Problem $7$: A very strong, but inept, shot putter puts the shot straight up vertically with an initial speed of $10\mathrm{.}6\frac{m}{s}.$

How long does he have to get out of the way if the shot was released at a height of $2\mathrm{.}8m,$ and he is $1\mathrm{.}9m$ tall?

$t=$