STU Ltd is considering purchasing a new machine to improve its manufacturing efficiency. Three machines are under review. The details of estimated yearly expenditure and sales are provided below. All sales are on cash basis. Corporate income-tax rate is 29%. Interest on capital may be assumed to be 8%.

Particulars	Machine X (Rs)	Machine Y (Rs)	Machine Z (Rs)
Initial investment	4,00,000	4,50,000	4,25,000
Estimated annual sales	6,75,000	7,25,000	7,00,000
Cost of production:
Direct material	58,000	63,000	60,000
Direct labour	68,000	73,000	70,000
Factory overhead	78,000	83,000	80,000
Administration cost	27,000	29,000	28,000
Selling & Distribution cost	19,000	21,000	20,000

The economic life of machine X is 3 years, while it is 4 years for the other two. The scrap values are Rs. 60,000, Rs. 65,000 and Rs. 62,000 respectively. Calculate the most profitable investment based on the payback period method.