Answer:
4.7 x 10^5, 5.2 x 10^5, 3.9 x 10^8
Explanation:
Since exponential growth far outclasses linear growth, it's safe to say that 3.9 x 10^8 is the greatest. Both of the other two share their second term, and thus their size is determined by the first term, so:
4.7 x 10^5 is the least
5.2 x 10^5 is the second largest
3.9 x 10^8 is the largest