Given:
Marginal propensity to consume (MPC) = 0.8
Equilibrium real output = $500 billion
Full-employment output = $540 billion
Find:
Change in government spending ΔG = ?
Computation:
Change in output ΔY = Full-employment output - Equilibrium real output
Change in output ΔY = $540 billion - $500 billion
Change in output ΔY = $40 billion
Change in output ΔY = [1 / (1 - MPC)] × ΔG
$40 billion = [1 / (1 - 0.8)] × ΔG
$40 billion = [1 / (0.2)] × ΔG
$40 billion = [5] × ΔG
ΔG = $40 billion / 5
ΔG = $8 billion
Change in government spending ΔG = $8 billion.