A Challenge From Khan Academy

I got an email this morning from KahnAcademy.ORG that reported 2 billion problems had been solved by 15 million students.

Here is the email:   You Got Us To 2 Billion

If you read the email you seen the question being asked:  How many problems per week would each of the current 15 million students need to solve so the  number of problems solved by this time next year comes out to be 10 billion.

Here is my solution: How To Make It To 10 Billion