... years,()×=T4(I, 10 years)$12,950$3,000 4 . 3 1 7==IRR 18% 0.1770.302 20% 18% –()+= 18% 0. 586 2%() 18= % 1.17% 19.17%=++=c 18. fm Page 282 Tuesday, July 19, 2005 5:22 PM262 Computer Securitybarraged ... of an investment.EXAMPLE 18. 1 PAYBACK PERIOD Assume:Cost of investment $ 18, 000Annual after-tax cash savings $ 3,000Then the payback period is:EXAMPLE 18. 2 PAYBACK PERIOD—TWO ... authentication devicesmay be used such as Security Dynamics’ SecurID (80 0-SECURID) and Vasco Data Security’s Access KeyII (80 0-2 38- 2726). Do not accept a prepaid call if it isnot from a network...