What is the probability of selecting 1 prime and 3 composite to form a 4 digit code? Prime p = {2} and Composite c = {4,6,8}.
If you cant explain it simply you dont understand it well enough!!!
- Genius
- Genius
Let the 2nd digit be prime. Then, the total number of selections = 4*4*3*2
Let the 3rd digit be prime. Then, the total number of selections = 4*4*3*2
Let the 4th digit be prime. Then, the total number of selections = 4*4*3*2
Total number of such cases = 4*4*4*3*2
Total number of combinations to form a 4 digit code(If 0 can be placed first and if repetition is not allowed) = 10*9*8*7
Probability = (4*4*4*3*2)/(10*9*8*7) = (4*2)/(5*3*7)= 8/105
p.s: One of the few Probability problems I solved in my life
