Maths
posted by bubbie on .
A locker combination has four nonzero digits. If no digit can be repeated and the first three digits are 123, what is the probability that the fourth digit is 4?
A. 1/6
B. 1/7
C. 1/8
D. 1/9

i am confused about this problem and would like some help. thank you x.x

Since the combination has already used 1, 2, and 3. Then the 4th digit must be either 4, 5, 6, 7, 8, or 9.
So the probability must 1 out of 6 or 1/6. 
thank you, ms. sue! that's what i thought it was but i was confused. :)

With your data, I am confused too. How many total numbers are there?
Since the first 3 numbers cannot be repeated, the answer = 1/(total3) 
You're welcome, bubbie.

nonzero digits = 19