Is the use of significant figures in each of the following statements appropriate? (a) The 2005 circulation of National Geographic was \(7,812,564 .\) (b) On July 1, 2005, the population of Cook County, Illinois, was $5,303,683 .(\mathbf{c})\( In the United States, \)0.621 \%$ of the population has the surname Brown. (d) You calculate your grade point average to be \(3.87562 .\)

For each statement: (a) The use of significant figures in the National Geographic circulation statement is appropriate since the circulation is a countable quantity. (b) The use of significant figures in the population of Cook County statement is appropriate as population should be reported with all significant figures for accuracy. (c) The use of significant figures in the percentage of Brown surnames statement is not appropriate; it would be better to round the percentage to one or two decimal places, e.g., \(0.62\%\) or \(0.621\%\). (d) The use of significant figures in the GPA calculation statement is not appropriate; it is recommended to round the value to one or two decimal places, e.g., \(3.88\) or \(3.9\).