Why do certain areas attract large population

Brian's school locker has a three-digit combination lock that can be set using the numbers 5 to 9 (including 5 and 9), without repeating a number. the probability that the locker code begins with a prime number is %. the probability that the last digit of the locker code is an odd number is %.

The capital of australia was located a. on a south-facing harbor d. between its two largest cities g. near the great barrier reef j. close to asia

What are two australian geographical features that hindered early exploration? western plateau gulf of carpentaria great barrier reef great dividing range