Andrews owed Martin, his accountant, a fee for services rendered. Andrews drew a check on his bank payable to Cash and signed it. He left the amount blank because he was not sure of the exact amount owed. On his way to Martins office, Andrews lost the check. Oliver found the check, filled it in for $500, and handed it to Ernest to satisfy a $500 debt that Oliver owed to Ernest. Ernest accepted the check in good faith as payment for the debt and immediately presented it to the drawee bank. The drawee bank refused to cash it because of a stop payment order.

a. Is Andrews liable to Ernest for the $500? Fully explain.

b. Would your answer be the same in the problem above if Andrews had made the original check payable to Martin and Oliver had signed Martins name prior to going to see Ernest, all other facts being the same? Fully explain your answer.