Answer:
The city population will first be below 48,000 in the year:
2022
Step-by-step explanation:
It is given that:
In 2010, a city population was 55,210
in 2011 the city population will be
(100-1.09)×55210/100=98.91×55210/100
= 0.9891×55210
in 2012 the city population will be
0.9891×0.9891×55210
we have to find number of years t such that

i.e. the thirteen years from 2010 we will have city population less than 48000
i.e. in the year 2022