Answer:
![\dfrac1{126}](https://tex.z-dn.net/?f=%5Cdfrac1%7B126%7D)
Step-by-step explanation:
9 all possible digits (1, 2, 3, 3, 4, 5, 6, 7, 8, 9)
4 digits and no digits repeated so
9•8•7•6 - number of all possible codes
4 even digits (2, 4, 6, 8)
4 digits and no digits repeated so
4•3•2•1 - number of all codes wich consists of all even digits
What is the probability that the lock code consists of all even didgit:
![\dfrac{4\cdot3\cdot2\cdot1}{9\cdot8\cdot7\cdot6}=\dfrac{1\cdot1\cdot1\cdot1}{9\cdot2\cdot7\cdot1}=\dfrac1{126}](https://tex.z-dn.net/?f=%5Cdfrac%7B4%5Ccdot3%5Ccdot2%5Ccdot1%7D%7B9%5Ccdot8%5Ccdot7%5Ccdot6%7D%3D%5Cdfrac%7B1%5Ccdot1%5Ccdot1%5Ccdot1%7D%7B9%5Ccdot2%5Ccdot7%5Ccdot1%7D%3D%5Cdfrac1%7B126%7D)