Try this:
Student = struct('Name',{'William','Romi','Russel','Mackly','Julia','Nimo','Bond','Mike','Rossel','Collom'},'Height',{174,168,182,166,156,172,171,163,166,174},'Weight',{76,62,72,60,62,80,90,48,56,72},'Gender',{'M','F','M','M','F','F','M','M','F','M'})
% Find which indexes have a weight of > 71
indexes = find([Student.Weight] > 71)
% List their names
for k = 1 : length(indexes)
thisIndex = indexes(k);
thisName = Student(thisIndex).Name;
fprintf('%s weighs %d kg.\n', thisName, Student(thisIndex).Weight)
end
