Look more carefully at your code. You have
if x>=60
statements between that and the next matching else or elseif or end statement are only executed if x is greater than or equal to 60
if x<60
end
if x<60
disp('Sorry, you failed.')
end
including those ones. You do not reach those statements unles x>=60 and if x>=60 then x<60 cannot possibly be true.
if rand*100 > 60
disp('Hip Hip Ho!')
else
disp('Hop Hep Hey!')
end
