A stone is thrown vertically upward with a speed of  $49{\mathrm{ms}}^{-1}.$Then the velocity of the stone, one second before it reaches the maximum height is

$\text{ Initial velocityu }=98\mathrm{m}/\mathrm{s}\text{. Acceleration due to gravity }\mathrm{g}=9.8{\mathrm{ms}}^{-2}$

$\text{ Time of ascent }{t}_{\mathrm{a}}=\frac{\mathrm{u}}{\mathrm{g}}=\frac{49}{9.8}=5\mathrm{s}$

Final velocity of the stone thrown upward after 4 seconds is

$\mathrm{v}=\mathrm{u}+\text{ at }\Rightarrow \mathrm{v}=49+(-9.8)\left(4\right)$

$\mathrm{v}=9.8{\mathrm{ms}}^{-1}$