Suppose that when your income increases by $300, your consumption expenditures increases by $240. Your marginal propensity to consume (MPC) is .
If your MPC was the same as the MPC for the economy as a whole, the expenditure multiplier for the economy would be .
Thus, a $4 million investment project would increase income by $ million in total.

The MPC is 0.8

The multiplier or k is 5

The increase in income would be $20 million.

Explanation:

The marginal propensity to consume (MPC) is the proportion of increased disposable income that consumers spend. It is a metric to quantify the induced consumption and how an increase in consumer spending occurs as a result of increase in income.

MPC is calculated as follows,

MPC = Change in consumer spending / change in income

MPC = 240 / 300

MPC = 0.8 or 80%

To calculate the multiplier, we simply use the following formula,

Multiplier or k = 1 / (1 - MPC)

k = 1 / (1 - 0.8)

k = 5

So, the expenditure multiplier for the economy would be 5.

To calculate the increase in income, we will multiply the investment amount by the expenditure multiplier.

Income increase = 4000000 * 5

Income increase = $20000000 or 20 million