Answer
$x ̅=74.85~min$
Work Step by Step
$x_1=First~Class~Midpoint=45$
$x_2=Second~Class~Midpoint=55$
$x_3=Third~Class~Midpoint=65$
$x_4=Fourth~Class~Midpoint=75$
$x_5=Fifth~Class~Midpoint=85$
$x_6=Sixth~Class~Midpoint=95$
$x_7=Seventh~Class~Midpoint=105$
$x ̅=\frac{Σx_if_i}{Σfi}=\frac{45\times8+55\times44+65\times23+75\times6+85\times107+95\times11+65\times43+105\times1+}{200}=74.85$
