I made this graph for you- the red is the 80%, and the green is the leftover 20%.
The answer is 4.23 the second meteorite wieghts 4.23 pounds
Both cylinder are similar
Volume of a cylinder is πr^2h
if we consider both has same radius as they are similar
Lets say V1 is volume of small cylinder and V2 is volume of big cylinder.
V1/V2=πr^2x5/πr^2xh
125/343=5/h
0.36=5/h
h=5/0.36
h=13.72 ft
You are correct there's at least one obtuse angle
+1/31 and -1/31
Hope this helps.