Calculate minimum wall thickness given a cylindrical prestressed water tank of internal diameter 30m over a depth of 7.5m and the permissible compressive stress at transfer is 13n/mm2 and the maximum compressive stress under working pressure is 1n/mm2 and the loss ratio is 0.75?

• A. 43.8
• B. 82.3
• C. 64.5
• D. 90.4