Suppose the spot price for gold is $1600, the 4-year futures price is $1850, and the 4-year (annual effective) risk-free rate is 3%. You would like to replicate the futures contract with a position in 1 ounce of gold and $X in cash.

What is the value of your cash position X?

(if you hold $100 in cash, write 100; if you borrow $100, write -100.)