Contracts of less than one year in IRP/PPP months, one, similar, contract, 319

hoangvu90

Say you have a contract for 3 months:

IRP formula (Schweser Book 1 Page 319):

1 + (intUS)(3/12)
---------------------
1+ (intUK)(3/12)


PPP formula (Schweser Book 1 Page 334):


[1 + infUS]^(3/12)
-----------------------
[1+ infUK]^(3/12)



Is there a reason one uses one and not the other or are they interchangeable/very similar after rounding?