60. Credit card debt. The average household credit card debt has been reported to be between $8000 and $10,000.

Often of interest is the average credit card debt carried by college students. In 2008, the average credit card debt for college students was reported to be $2200 based on 12,500 responses. A year earlier it was reported to be $2190 based on survey of 8200 college students. The standard error of the difference in mean credit card balances was $1.75.

a) Has the average credit card balance carried by college students increased significantly? Cite appropriate statistical evidence to support your conclusion.

b) Is this a meaningful difference to the typical student? Is it meaningful to a credit card company?

c) The sample size in 2008 is one and a half times that in 2007. Does this make the results more or less convincing?

Explain.