Answer
$7.91\frac{Km}{s}$
Work Step by Step
We know that
$v_i=\sqrt{\frac{GM_E}{R_E}}$
We plug in the known values to obtain:
$v_i=\sqrt{\frac{6.67\times 10^{-11}(5.97\times 10^{24})}{6.37\times 10^6}}$
$v_i=7910\frac{m}{s}$
$\implies v_i=7.91\frac{Km}{s}$
