The slope of the AE curve is .80. What is the expenditure multiplier? Everything else the same, by how much does equilibrium aggregate expenditure increase if
a. exports increase from $1.75 trillion to $2.25 trillion?
b. government expenditure on goods and services decrease from $2.0 trillion to $1.8 trillion?
c. investment increases from $1.2 trillion to $2.3 trillion?