Math
posted by Golkhadi nep .
In the summer of 2008 the population of cuckoos in an area was estimated as 560 pairs. If the numbers returning are declining at 4% each year, calculate
(a) the number of pairs of cuckoos in the area in the summer of 2009;
(b) the number of pairs of cuckoos in the area in the summer of 2020

so my guess is that you would start with what ya got
2008 5604%
2009 559.964%
2010 559.924%
(continue til you get to 2020)
sooo;
a.) 559.92
b.) 559.52 
If the population declines at 4%, it means that the surviving population is 96% of the previous year.
In the summer of 2008, there were 560 pairs. So in the summer of 2009, there were 560*(96/100)
= 537.6 pairs (theoretically)
= 538 pairs
In the summer of 2009, the population declined again to 96% of the theoretical population of 2008, thus
537.6*(96/100)
=516.1 pairs (theoretically)
= 516 pairs (rounded)