The figures are invented. In an economy the marginal propensity to save (MPS) is 0.25, the marginal propensity to tax (MPT) is 0.10 and the marginal propensity to import (MPM) is 0.15. (i) Calculate the Keynesian multiplier. [2] (ii) Calculate the change in GDP caused by a $9 billion increase in investment, assuming constant prices and spare capacity. [2]

HL Paper 3-style calculation (standalone practice; not an IB question).