Positive net exports increase aggregate expenditures beyond what they would be in a closed economy and thus have an expansionary effect.The multiplier effect also is at work.Positive net exports will lead to a positive change that is greater than the amount of the initial change.Negative net exports decrease aggregate expenditures beyond what they would be in a closed economy and thus have a contractionary effect.The multiplier effect also is at work here.Negative net exports lead to a negative change in equilibrium GDP that is greater than the initial change.
(a) This should increase GDP because an increase in consumer wealth would lead to an increase in consumer spending which would shift the aggregate expenditures curve upward to a higher equilibrium output level.
(b) The probable effect of a sharp rise in stock prices would be to increase in consumption by shareholders who have seen an increase in wealth, thus shifting the aggregate expenditures curve upward and increasing the equilibrium level of GDP.It also could encourage business investment with funds gained by issuing new shares of stock at the now higher prices.This would also tend to increase GDP.
(c) This should increase GDP because of the impact on new investment spending and possible increased consumer purchases of goods having the new technology.The aggregate expenditures curve will shift upward and real output will rise.
(d) A sharp increase in the interest rate would limit consumer durable purchases and also limit investment spending.Both of these events would cause a downward shift in aggregate expenditures causing a decrease in GDP.
When underlying conditions change, but the price cannot change, firms take their signals from unplanned changes in their inventories.