I know the correct answers to these questions i just need to know the math behind them should the number change. Thank you in advance!

(1) If the required reserve ratio is 15 percent, currency in circulation is $400 billion, checkable deposits are $800 billion, and excess reserves total $0.8 billion, then the M1 money multiplier is

A) 2.5.

B) 1.67.

C) 2.3.

D) 0.651

(2) In the simple deposit expansion model, a decline in current deposits of 1,000 when the required reserve ratio is equal to 20 percent implies that the ECB

A) sold 200 in government bonds.

B) sold 500 in government bonds.

C) purchased 200 in government bonds.

D) purchased 500 in government bonds.

(3) IIf a bank has 200,000 of current (checkable) deposits, a required reserve ratio of 20 percent, and it holds

80,000 in reserves, then the maximum deposit outflow it can sustain without altering its balance sheet is

A) 50,000.

B) 40,000.

C) 30,000.

D) 25,000

(4) If the required reserve ratio is 15 percent, the simple deposit multiplier is

A) 15.0.

B) 1.5.

C) 6.67.

D) 3.33.