有没有数学大佬，算一个纸牌概率

program test;
const
deck: array[0..51] of integer = (1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,6,6,6,6,7,7,7,7,8,8,8,8,9,9,9,9,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10);

var
draw: array[1..5] of integer;
i, j, k, sum, suc: integer;
dup: boolean;

begin
suc := 0;
for i := 1 to 10000000 do begin
sum := 0;
for j := 1 to 5 do begin
repeat
dup := false;
draw[j] := random(52);
for k := 1 to j - 1 do
if draw[j] = draw[k] then
dup := true;
until not dup;
sum := sum + deck[draw[j]];
end;
if sum > 30 then
inc(suc);
end;
writeln(suc);
readln;
end.