Answer
$x ̅=27.7~min$
Work Step by Step
$x_1=First~Class~Midpoint=5$
$x_2=Second~Class~Midpoint=15$
$x_3=Third~Class~Midpoint=25$
$x_4=Fourth~Class~Midpoint=35$
$x_5=Fifth~Class~Midpoint=45$
$x_6=Sixth~Class~Midpoint=55$
$x_7=Seventh~Class~Midpoint=65$
$x_8=Eighth~Class~Midpoint=75$
$x_9=Nineth~Class~Midpoint=85$
$x ̅=\frac{Σx_if_i}{Σfi}=\frac{5\times125+15\times271+25\times186+35\times121+45\times54+55\times62+65\times43+75\times20+85\times13}{895}=27.7$
