In April 2011, the money supply, as measured by M1, was approximately $1,917 billion. The monetary base

Question:

In April 2011, the money supply, as measured by M1, was approximately $1,917 billion. The monetary base was approximately $2,494 billion.
a. What was the value of the money multiplier?
b. Why is the value of the money multiplier typically greater than 1? What is the key reason that it was less than 1 in 2011?