Ethem S. answered 10/19/19
I will assume that $10,000 is the total amount (principle and interest) at the end of year 4. (Otherwise, present value is $10,000 :-) )
Let's call present value x. Per week interest is 6/52 %, 4 years is 4*52 weeks
After 4 years, with compounded interest weekly, we will have
x * (1+6/52/100)(4*52)=x * (1+0.001154)208 = x*1.271 = 10000
x = 10000/1.271 = $7867.82