In which year, the percentage decrease or increase in income is the highest with respect to the previous year

$\begin{align}
  & \text{a) 2006} \\
 & \text{b) 2010} \\
 & \text{c) 2007} \\
 & \text{d)}\text{ 2008} \\
\end{align}$

Hint: Now we are given with the graph of the income vs year. Hence we can find the increase or decrease in income each year. Accordingly we can find the increase or decrease percentage by the formula \[\dfrac{\text{increase/decrease in income}}{\text{previous value}}\times 100\] . Now comparing the values we can find the maximum value and hence the corresponding year.

Complete step by step answer:
Now we are given a graph which represents the income of a company in the years 2006, 2007, 2008, 2009, 2010. Now comparing the values of y axis with each corresponding year we get the income of the company. Note that the income is in 100 crores.
Hence now extracting the information from graph we get
Let us form a table for the data.
For this we will form two columns
First column represents the number of years.
Second column represents the income of 100 crores.




Now in 2006 the income was 30 and in 2007 the income was 50.
Hence we can see the income has increased by 20.
Now Hence the percent increase is $\dfrac{20}{30}\times 100=66.66$
Hence in 2007 the percentage increase of income was 66.66 percent.
Now consider the year 2008. In 2008 the income was 60 while in 2007 it was 50.
The net decrease is 60 – 50 = 10
Hence the percentage decrease is $\dfrac{10}{50}\times 100=$20
Hence the decrease of income in 2008 was 20 percent.
Now consider the year 2009. In 2009 the income was 70. Since the income was 60 in 2008 we can say that the income was increased by 10. Hence the percentage increase is $\dfrac{10}{60}\times 100$ = 16.66
Hence the income was increased by 16.66 percent in 2009.
Now consider 2010.
The net income in 2010 is 50, while it was 70 in 2009
Hence the net decrease is 70 – 50 = 20.
Hence the decrease percentage is nothing but $\dfrac{20}{70}\times 100=28.57$
Hence the income was decreased by 28.57 percent in 2010.
Hence we can say that the maximum increase or decrease in income in terms of percentage was in the year 2007, since the income was increased by 66.66 percent.

So, the correct answer is “Option C”.

Note: Note that here we have to calculate percentage increase or percentage decrease for each year. The net increase can be the same for two years but the percentage increase might change. For example, in 2007 the net increase was 20 and in 2010 the net decrease was 20. But still the percentage is different for both years. Also note that the incomes are given in 100 crores. We did not convert the income while calculating percentage though it won’t make a difference in percentage increase or percentage decrease.