Final answer:
The information provided does not directly state the ratio of contractors to U.S. soldiers in Afghanistan in 2008, but it does highlight the significant role and cost of private military contractors in the conflict.
Step-by-step explanation:
According to the provided information, the answer to the student's question about the number of contractors for every U.S. soldier supporting the United States in the Afghanistan War as of 2008 is not directly stated. However, the information sheds light on the involvement of private military contractors, such as those from Blackwater USA highlighted in the March 2004 incident, the growing insurgency, and significant monetary costs associated with the conflicts in Iraq and Afghanistan. By 2013, the war's expenses had approached a conservative estimate of $1.7 trillion.
The texts also discuss the escalation in the number of U.S. forces in Afghanistan, reaching about 100,000 in 2010, with a schedule to begin withdrawal between mid-2011 to the end of 2014. The ratio of contractors to soldiers may be contextually inferred given the significant reliance on private military contractors, but the specific ratio for 2008 would require additional data from that particular year which is not provided in the given extracts.