Answer
$76.67$%
Work Step by Step
It is the summation of the relative frequencies of "2", "3", "4" and "5": $0,3000+0,3333+0,1167+0,0167=0.7667=76.67$%
OR:
The relative frequency of couples married 7 years that have up to one child is the cumulative relative frequency for "1" $=0.2333$
The relative frequency of couples married 7 years that have at least two children $=1-the~relative~frequency~of~couples~married~7~years~that~have~up~to~one~child=1-0.2333=0.7667=76.67$%
