What is the average number of offspring produced by individuals that survive to at least age class 6

Age (x) o 1 2 3 4 5 6 7 nx 1000 990 980 960 900 620 300 o 1.00 0.99 0.98 0.96 0.90 0.62 0.30 0.00 10 10 20 60 280 320 300 n/a 0.01 0.01 0.02 0.06 0.31 0.52 1.00 n/a 0.00 0.00 0.00 1.25 0.90 0.35 0.00 0.00 0.99 0.99 0.98 0.94 0.69 0.48 0.00 n/a Ixbx o O O 1.2 0.81 0.217 o o 2.227 2.249 2.272 2.32 1.141 0.35 o o