A small combination lock on a suitcase has 3 wheels, each labeled with the 10 digits 0 to 9. How many 3 digit combinations are possible if no digit is repeated? If digits can be repeated? If successive digits must be different?
a) The number of different 3 digit combinations possible if no digit is repeated is…..?
b) The number of different 3 digit combinations possible if digits can be repeated is …..?
c) The number of different 3 digit combinations possible if successive digits must be different is …..?
Solution:-
a) 10*9*8 = 720
b) 10*10*10=1000
c) 10*9*9= 810
How did you get the answer for C using the counting principle?