Suppose a manager wants to borrow using a Treasury security she currently holds as collateral. The portfolio manager can enter a repo with a dealer firm that would provide financing at a $10\%$ repo rate. The repo term is $30$ days and the nominal amount of the contract is USD$100$ million. Answer the following questions:

$1)$ What is the dollar interest cost that the manager needs to pay?

$2)$ What is the total amount being borrowed?

$3)$ What is the risk that borrower does not buy back the collateral?