Answer:
(B) $20 billion
Explanation:
Given a certain level of MPC, an increase in government spending (G) by a certain amount translates to an increase in aggregate demand (AD) through the relationship below.
[tex]ΔAD = \frac{ΔG}{1 - MPC}[/tex]
where Δ means change.
Therefore, given ΔAD of $50 billion, and MPC of 0.6,
[tex]ΔAD = \frac{ΔG}{1 - MPC}[/tex]
= [tex]50 = \frac{ΔG}{1 - 0.6}[/tex]
= [tex]50 = \frac{ΔG}{0.4}[/tex]
= ΔG = 50 * 0.4 = 20
Therefore, increase in government purchases = $20 billion.