A shift to the left of a supply curve is caused by:
an increase in the number of sellers.
a technological improvement.
an increase in the cost of an input.
an increase in the number of buyers.
A shift to the left of a supply curve is caused by an increase in the cost of an input. To understand this, it's important to understand the concept of supply and the factors that affect it.
Supply refers to the quantity of a good or service that sellers are willing and able to provide to the market at different prices. The supply curve is an upward sloping curve that shows the relationship between the price of a good and the quantity of the good that suppliers are willing to produce and sell.
When there is a shift in the supply curve, it means that the quantity supplied at each price has changed. In this case, a shift to the left means that the quantity supplied at each price has decreased.
Now, let's go through the options provided and analyze which one could cause this leftward shift:
1. An increase in the number of sellers: An increase in the number of sellers would actually result in a rightward shift of the supply curve, as there would be more producers supplying the market, leading to an increase in the quantity supplied.
2. A technological improvement: Technological improvements typically lead to an increase in production efficiency, which often results in an increase in the quantity supplied. Therefore, a technological improvement would cause a rightward shift, not a leftward shift, of the supply curve.
3. An increase in the cost of an input: This is the correct answer. When the cost of inputs used in the production of a good or service increases, it becomes more expensive for producers to produce that good. As a result, they will supply less quantity at each price level, leading to a leftward shift of the supply curve.
4. An increase in the number of buyers: The number of buyers is a factor that affects demand, not supply. Therefore, an increase in the number of buyers would not cause a shift in the supply curve.
In conclusion, the correct answer to the question is: an increase in the cost of an input. This is the factor that would cause a leftward shift in the supply curve.