In Country C, the number of transactions made by various noncash metho

Official Explanation

Of the four noncash methods represented in the graph, only paper check showed an increase from 2006 to 2009. Indeed, the number of paper check transactions increased from 24 million in 2006 to 30 million in 2009. This indicates a percentage increase of \((\frac{30−24}{24})\)(100%)=25%.

The correct answer is paper check.

The average value of all credit card transactions in 2006 was \(\frac{T}{22,000,000}\), where T is the total value of all credit card transactions in 2006. If the total value of all credit card transactions in 2009 was 10% more than the total value of all credit card transactions in 2006, then the total value of all credit card transactions in 2009 was 1.1T. Therefore, the average value of all credit card transactions in 2009 was \(\frac{1.1T}{20,000,000.}\)
If the average value of credit card transactions increased by x% from 2006 to 2009, then

\((\frac{100+x}{100})(\frac{T}{22,000,000})=\frac{1.1T}{20,000,000}\)

Therefore,

\(\frac{100+x}{100} =\) \(\frac{(1.1)(22,000,000)}{20,000,000}\)

\(= \frac{121}{100}\)

Thus, 100 + x = 121, so x = 21.

The correct answer is 21.0.