Answer: $16 billion, and also by $16 billion if the securities are purchased directly from commercial banks
Step-by-step explanation:
Since we are given a 25% reserve ratio, then the money multiplier will therefore be:
= 1/25%
= 1/0.25
= 4.
Therefore, the money supply will be increased to (4 billion × 4) = 16 billion.
Therefore, the answer is "$16 billion, and also by $16 billion if the securities are purchased directly from commercial banks".