a) Refer to Figure 1. Investment is b) Refer to Figure 1. Equilibrium expenditure is c) Refer to Figure 1. When real GDP is $300 billion, real GDP 1) is less than aggregate planned expenditure by $25 billion, and firms decrease production 2) exceeds aggregate planned expenditure by $25 billion, and firms increase production. 3) is the same as aggregate planned expenditure, and firms do not change production. 4) exceeds aggregate planned expenditure by $25 billion, and firms decrease production. 5) exceeds aggregate planned expenditure by $50 billion, and firms increase production. d) Refer to Figure 1. When real GDP is $100 billion, 1) real GDP is less than aggregate planned expenditure, and firms increase production. 2) aggregate planned expenditure is greater than real GDP, and firms decrease production. 3) real GDP is greater than aggregate planned expenditure, and firms decrease production