Answer:
1) Monetary base (B) = C + R
B = $20 billion + $10 billion = $30 billion
2) Demand deposits
First we write the currency-deposit ratio equation:
CR = C/D
0.2 = $20 bilion/D
D*0.2 = $20 billion/D*D
0.2D = $20 billion
0.2D*10 = $20 billion *10
2D = $200 billion
D = $200 billion / 2
D = $100 billion
Which is consistent with the currency-deposit ratio of 0.2 because currency is $ 20 billion and deposits are $ 100 billion.
3) Money multiplier (m)
m = cr + 1/ cr + rr
m = 0.2 + 1/0.2 + 0.1
m = 4
4) Money Supply (M)
M = m x B
M = 4 x $30 billion
M = $120 billion
5) Increase in monetary base for a 10% increase in money supply:
ΔM = ΔR * m
10%ΔM = ΔR * 4
10%/4 = ΔR * 4/4
0.025 = ΔR
ΔR = 2.5%
The FOMC needs to increase banks reserves by 2.5%, in order to increase the money supply by 10%.
The FOMC would do this by buying US Treasury notes in the Open Market. The dollars it would use to buy these notes enter the monetary base in the form of excess reserves, and commercial banks then would use these excess reserves to make loans, and this would ultimately increase the money supply.