Answer: $1.57 billion
Step-by-step explanation:
Given that,
Government purchases multiplier = 1.57
Increase in government purchases = $1 billion


Change in Real GDP = 1.57 × 1,000,000,000
= $1,570,000,000
= $1.57 billion
Hence, $1 billion increase in government purchases will lead to increase equilibrium real GDP by $1.57 billion.