|Noah ||502 ||448 ||950||502||448||950||502||448||950|
|Serug ||30||200||230||130||200 ||330||130||100||230|
The figures for Terah are to his first son. Genesis 12 and Acts 7 imply that Abram was 75 at Terah's death and therefore Terah was 130 when Abram was born, so the year in which Abram was born is 75 years prior to Terah's death.
So we can calculate the year of the flood, the year in which Abram was born and the time elapsed.
Again I prefer the Masoretic. There seems to be a rationale for lengthening the times so as to make one's culture ancient, but to shorten the timeframe would seem unlikely. As there is no summary age as there is in Genesis 5, the fact of the systematic change in Genesis 5 and the frequent difference of 100 years suggests this was conscious, not accidental.
If the Masoretic is original, then the Samaritan has added years till the year of the first child but subtracted them for the remaining years leaving the total calculated age the same even though this is not given in Scripture. The exceptions being Eber and Nahor. The interesting thing about Eber is that the age after the son was born is 100 years less than the Septuagint. Was there are further Hebrew text which gave 370 years to Eber after his son was born?
Explaining the derivation of the Septuagint is difficult. Arphaxad, Salah and Eber don't appear to derive from the Masoretic at all. A smoothing effect (so that the ages drop off steadily from 900 years) is not clearly apparent and is an inadequate explanation.
If the Masoretic is correct we have the situation where Abram potentially could have known his ancestors. Abram was born in 2008 AM. Note the year of death.
Of Abram's 10 ancestors following the Flood, 7 of them were alive at his birth. Noah died 2 years before Abram was born. And Peleg and Nahor also died prior to his birth. The others were all alive. Shem, who had seen the Flood, only died 25 years before Abram, Abram would have been 150 years old and Isaac 50. Eber, from whom the Hebrews derive their name, outlived Abram!