The pressure generated by the piston at the input cylinder must be:
p = F / A = 250 lb-f / 30 in^2
The pressure generated by the piston at the output cylinders is p = F / A = 775 lb-f / A.
Pascal principle rules that both pressures are equal, so:
250 lb-f / 30 in^2 = 775 lb-f / A => A = 775 lb-f * 30 in^2 / 250 lb-f = 93 in^2
Gvien that each output cylinder are 30in^2 you need 93 / 30 = 3.1 cylinders.
Which means that at least you need 4 cylinders to generate a force at least of 775 lb-f.
Answer: 4
