Answer:
My friend is incorrect. It will take another 200 years for a flood of that sort to occur again
Explanation:
The said friend mentioned that the flood in 2010 was a 100-year flood; This indicates it lasted from 1910 to 2010 which gives a 100 years
Then in 2009, the flood lasted for 200 years which indicates the flood had just a year difference between that of 2010 and that of 2009. Jointly, the floods lasted 200 years with just a year difference if analyzing between 2009 and 2010.
Therefore, It will take another 200 years for a flood of that sort to occur again with of course, a year difference in interval between that of 2009 and 2010
