A high pressure cylinder consists of a steel tube with inner and outer diameters 30 and 60mm respectively. It is jacketed by an outer steel tube, having an outer diameter of 90mm. Maximum principal stress induced is 80N/mm². In service the cylinder is further subjected to an internal pressure of 25MPa. Calculate the tangential stress in compound cylinder.$

• A. -6.75[(45/r) ¬¨¬®‚Äö√¢¬ß + 1]
• B. +3.75[(45/r) ¬¨¬®‚Äö√¢¬ß +1]
• C. -3.75[(45/r) ¬¨¬®‚Äö√¢¬ß +1]
• D. -3.75[(45/r) ¬¨¬®‚Äö√¢¬ß -1]