In which month is the average percentage increase for the four commodities the lowest? (Those months where decrease rook place to be ignored)

From above given graph we can see that there are two months for which graph is going Up.
By seeing the graph we can see that graph is going up for the month of May and June.
So required answer will be May and June only.

Compound interest = P(1 + r)^t - P
or Compound interest = P[(1 + r)^t - 1]
where P = the principal investment amount (the initial deposit or loan amount)
r = the annual interest rate
t = the number of years the money is invested or borrowed for.
Required amount of interest earned by Madhava in 2007 = 15000[(1+ 15/100)² - 1]
= 15000[(115/100)² - 1]
= 15000[(23/20)² - 1]
= 15000[(23 x 23 /20 x 20) - 1]
= 15000[ (529/400) - 1]
= 15000[(529 - 400)/400]
= 15000 x 129/400
= 19350/4
= Rs. 4837.50

Simple interest formula I = P x R x T where
P is the Principal amount of money to be invested at an Interest Rate R% per period for T Number of Time Periods.

Interest received in 2009 from Company B = 20000 x 145 x 1/100 = 2900
Hence, their amount = 20000 + 2900 = Rs. 22900
Interest will be received in 2010 from company A = 22900 x 12.5 x 1/100 = Rs. 2862.50
Hence, total amount of interests for both years = 2900 + 2860.50 = Rs. 5762.50

We can apply the formula to calculate the interest amount
I = P x R x t where
A = Total Accrued Amount (principal + interest)
P = Principal Amount
I = Interest Amount
R = Rate of Interest per year as a percent;
t = Time Period involved in years

For Company A in 2006,
Principle amount = 10000
Rate of interest = 11.5 % ( As per given graph for company A in 2006)
Time = 1 year
The interest amount received by Samir in 2007 I = P x R x t
The interest amount received by Samir in 2007 = 10000 x 11.5 x 1/100= 10000 x 115 x 1/10 x 100 = 10 x 115 = 1150
Total amount received by Samir in 2007 = Interest amount + Principal amount = 10000 + 1150 = 11150
Again For Company A in 2007,
Principle amount = 11150
Rate of interest = 15 % ( As per given graph for company A in 2007)
Time = 1 year
The interest amount received by Samir in 2008 I = P x R x t
The interest amount received by Samir in 2008 = 11150 x 15 x 1/100 = 1115 x 15/10 = 1115 x 3/2 = 3345/2 = 1672.5
Total amount received by Samir in 2008 = Interest amount + Principal amount = 11150+ 1672.5 = 12822.50
Hence, their interest = 12822.50 - 10000 = 2822.50
For Company B in 2006,
Principle amount = 10000
Rate of interest = 13.5 % ( As per given graph for company B in 2006)
Time = 1 year
The interest amount received by Samir in 2007 I = P x R x t
The interest amount received by Samir in 2007 = 10000 x 13.5 x 1/100= 10000 x 135 x 1/10 x 100 = 10 x 135 = 1350
Total amount received by Samir in 2007 = Interest amount + Principal amount = 10000 + 1350 = 11350
Again For Company B in 2007,
Principle amount = 11350
Rate of interest = 14 % ( As per given graph for company B in 2007)
Time = 1 year
The interest amount received by Samir in 2008 I = P x R x t
The interest amount received by Samir in 2008 = 11350 x 14 x 1/100 = 1135 x 14/10 = 1135 x 7/5 = 227 x 7 = 1589
Total amount received by Samir in 2008 = Interest amount + Principal amount = 11350+ 1589 = 12939
Since, their interest = 12939 - 10000 = Rs. 2939
Hence, difference between the interests earned = 2939 - 2822.50 = Rs. 116.50
If Samir had invested the amount in company B for both years then he would get Rs. 116.50 more.

From above graph ,
Since , In July and August months did all the commodities show decline or no increase from the previous months.
Required answer will be July and August only .

From above given graph ,
For D commodity is the percent increase in sale the highest in May from January.
Option E is correct answer.