In the problem we have 2 periods 2004-2006 (3 years) and 2007-2012 (6 years).
For the first period the average revenue is (1100+700+300)/3=700
The average costs is (400+900+500)/3=600
So, the average profit is 700-600=100
Let assume that both revenue and costs increased in the second period by x percents. Then new average revenue for 2007-2012 is 700(1+x/100), new average costs is 600(1+x/100).
To calculate average profit for the whole total period 2004-2012 we need to sum all revenues, subtract all costs and divide by 9.
Total revenues=3*700+6*700(1+x/100)
Total costs=3*600+6*600(1+x/100)
Total profit=3*100+6*100(1+x/100)
Average profit=Total profit/9=100/3+200/3(1+x/100)
We know that it is equal to 300
100/3+200/3(1+x/100)=300
200(1+x/100)=800
1+x/100=4
x=300
So, both revenue and costs increased by 300% in the second period, thefore the ratio of revenues is 1/4.
The answer is C
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