Solution and Explanation:
The follwoing is used to calcuate the internal rate of return for both the projects
Project T-Shirt
Present value = -15,000 , N = 4 , PMT = 8,000
Solving for the Internal rate of return = 39.08%
Project Board Shorts
Present value = -25,000 , N = 5 , PMT = 12,000
Solving for the Internal rate of return = 38.62%
Based on Internal rate of return analysis, Billabong Tech should choose project T-Shirt.