probability
posted by steph on .
What is the probability that an 8 digit numbers contains "97"?

if the first 2 digits are 97 then there are 10^6 ways of picking the other 6 digits.
Since the 97 can appear in 7 different places in an 8digit number, that means there are 7,000,000 ways to make an 8digit numbers with 97 in it. 
so, that would be a probability of 7*10^6/9*10^7 = 7/90 = .0777