Answer:
1/8 = (1/2)^3
This implies the sample has decayed for 3 half lives
3 * 5730 yrs = 17,200 years
Explanation:
Value of the cross-sectional area is as follows.
A =
= 3.45 
The given data is as follows.
Allowable stress = 14,500 psi
Shear stress = 7100 psi
Now, we will calculate maximum load from allowable stress as follows.

= 
= 50025 lb
Now, maximum load from shear stress is as follows.

= 
= 48990 lb
Hence,
will be calculated as follows.

= 48990 lb
Thus, we can conclude that the maximum permissible load
is 48990 lb.