If the sales revenues in the years 2005, 2006 and 2007 increase by 20%, 25% and 30% respectively and the costs of production in the years 2007, 2008 and 2009 increase by 20%, 25% and 35% respectively, what will be the difference between average sales revenue and average cost of production?

Increase in the sales revenue in the year :

2005 = $$\frac{120}{100}$$ * 725 = 870 k

2006 = $$\frac{125}{100}$$ * 550 = 687.5 k

2007 = $$\frac{130}{100}$$ * 600 = 780 k

=> Average Revenue = $$\frac{870 + 687.5 + 780}{3}$$ = 779.17 k

Increase in production cost in the year :

2007 = $$\frac{120}{100}$$ * 400 = 480 k

2008 = $$\frac{125}{100}$$ * 500 = 625 k

2009 = $$\frac{135}{100}$$ * 525 = 708.75 k

=> Average cost = $$\frac{480 + 625 + 708.75}{3}$$ = 604.58 k

$$\therefore$$ Required difference = 779.17k - 604.58k

= Rs. 174.59 thousand