Given the following trends for the cost of rotating disk storage, estimate the year that you will be able to purchase a petabyte of storage (10^15 bytes = 1000 terabytes = 1 million gigabytes) for under $500.

In 2010 a petabyte of storage costs about $300,000)

Year	2000	2005	2010
$/MB	0.01	0.005	0.0003

HINT: In the 10 years between 2000 and 2010, the cost for 1 MB of rotating disk storage dropped by a factor of about 30 2^5. So lets assume that the cost is dropping by a factor of 2 about every 2 years, and this trend continues.

Explain your answer.