The structure of $X$ is

Modern farmers have been able to increase rice production by $50\%$ using which of the following?

Let $h(x)$ be differentiable for all $x$ and let $f(x) = (kx + e^x) h(x)$. Where $k$ is some constant. If $h(0) = 5$,$h'(0) = -2$,and $f'(0) = 18$,then the value of $k$ is equal to:

$A$ body projected vertically upwards crosses a point twice in its journey at a height $h$ just after $t_1$ and $t_2$ seconds. Maximum height reached by the body is

The variance of $50$ observations is $7$. If each observation is multiplied by $6$ and then $5$ is subtracted from it,then the variance of the new data is

$A$ container is filled with water $(\mu = 1.33 \approx 4/3)$ up to a height of $33.25 \, cm$. $A$ concave mirror is placed $15 \, cm$ above the water level. The image of an object placed at the bottom is formed by the mirror at $25 \, cm$ below the water level. The focal length of the mirror is: (in $, cm$)