Given an MPC of 0.8, which of the following is not true? 1) a $10 billion increase in investment will increase income by $50 billion 2) a $5 billion tax cut will raise aggregate income by $25 billion 3) the MPS must be 0.2 4) a $20 billion increase in government spending will increase income by $100 billion Solution 3) the MPS must be 0.2 .