Question

The velocity $v($in $\text{m/s})$ of a train in time $t($in $\text{sec})$ is given by $v=52+7t$. The minimum time $t($in $\text{sec})$ when its velocity is atleast $73\text{m/s}$ is

• A. $2$
• B. $2.5$
• C. $3$
• D. $4$

Answer 1

The correct option is C $3$

$v\ge 73$
$\Rightarrow 52+7t\ge 73$
$\Rightarrow 7t\ge 21$
$\Rightarrow t\ge 3$