Dari 10 soal jika di perbolehkan mengerjakan 5 soal dengan soal no 5 dan 10 harus dikerjakan maka kemungkinan soal yang dikerjakan ada

1 = {1,2,3,5,10}

2 = {1,2,4,5,10}

3 = {1,2,5,6,10}

4 = {1,2,5,7,10}

5 = {1,2,5,8,10}

6 = {1,2,5,9,10}

7 = {1,3,4,5,10}

8 = {1,3,5,6,10}

9 = {1,3,5,7,10}

10 = {1,3,5,8,10}

11 = {1,3,5,9,10}

12 = {1,4,5,6,10}

13 = {1,4,5,7,10}

14 = {1,4,5,8,10}

15 = {1,4,5,9,10}

16 = {1,5,6,7,10}

17 = {1,5,6,8,10}

18 = {1,5,6,9,10}

19 = {1,5,7,8,10}

20 = {1,5,7,9,10}

21 = {1,5,8,9,10}

22 = {2,3,4,5,10}

23 = {2,3,5,6,10}

24 = {2,3,5,7,10}

25 = {2,3,5,8,10}

26 = {2,3,5,9,10}

27 = {2,4,5,6,10}

28 = {2,4,5,7,10}

29 = {2,4,5,8,10}

30 = {2,4,5,9,10}

31 = {2,5,6,7,10}

32 = {2,5,6,8,10}

33 = {2,5,6,9,10}

34 = {2,5,7,8,10}

35 = {2,5,7,9,10}

36 = {2,5,8,9,10}

37 = {3,4,5,6,10}

38 = {3,4,5,7,10}

39 = {3,4,5,8,10}

40 = {3,4,5,9,10}

41 = {3,5,6,7,10}

42 = {3,5,6,8,10}

43 = {3,5,6,9,10}

44 = {3,5,7,8,10}

45 = {3,5,7,9,10}

46 = {3,5,8,9,10}

47 = {4,5,6,7,10}

48 = {4,5,6,8,10}

49 = {4,5,6,9,10}

50 = {4,5,7,8,10}

51 = {4,5,7,9,10}

52 = {4,5,8,9,10}

53 = {5,6,7,8,10}

54 = {5,6,7,9,10}

55 = {5,6,8,9,10}

56 = {5,7,8,9,10}

Jadi kemungkinannya ada 56 kemungkinan