Final answer:
The amount of required reserves at the commercial bank is $27,750,000, and the average percentage of required reserves is 9.25%.
Step-by-step explanation:
To calculate the amount of required reserves at a commercial bank, we need to follow the reserve requirements set by the Federal Reserve. In this case, the bank has $300 million in customer demand deposits.
First, we calculate the reserves required on the first $5 million of deposits, which have a reserve requirement of 0%. So, the required reserves for this portion is $0.
Next, we calculate the reserves required on additional deposits up to $30 million, which have a reserve requirement of 3%. This portion is $30 million - $5 million = $25 million. So, the required reserves for this portion is 3% of $25 million, which is $750,000.
Finally, we calculate the reserves required on deposits over $30 million, which have a reserve requirement of 10%. This portion is $300 million - $30 million = $270 million. So, the required reserves for this portion is 10% of $270 million, which is $27 million.
In total, the amount of required reserves is $0 + $750,000 + $27 million = $27,750,000.
To calculate the average percentage of required reserves, we divide the amount of required reserves by the total amount of deposits: $27,750,000 / $300,000,000 = 0.0925, or 9.25%.