Explanation
The minimum variance hedge ratio answers the question of how much of the hedge to buy to hedge a given position. It minimizes the combined volatility of the primary and the hedge position. The minimum variance hedge ratio is given by the expression [ (x) / (y) ] * (x,y)]. Effectively, this is the same as the beta of the primary position with respect to the hedge.
In this case, the hedge ratio is = 10%/9% * 0.9 = 1