Answer: $160 billion
Explanation:
The government purchases multiplier refers to the increase in real GDP in dollar terms as a result of a dollar of government purchases in the economy. For instance, if the multiplier is 5 and the government spends $10, real GDP increases by: 5 * 10 = $50
The gap here is $800 billion. Given a government purchases multiplier of 5.0, the amount that the government needs to spend is:
= Gap / Multiplier
= 800 / 5
= $160 billion