In the short-run commodity X and commodity Y are supplied jointly, which of the following is correct?

  • A An increase in demand for X will increase supply of Y
  • B An increase in demand for X will leave the supply of Y unchanged
  • C An increase in demand for Y will raise the price of X
  • D An increase in demand for X will cause less of Y to be produced
waec 2009economics

The correct answer is A. An increase in demand for X will increase supply of Y

An increase in demand for X will increase the supply of Y because joint supply describes a situation where an increase or decrease in the supply of one good leads to an increase or decrease in the supply of another by-product. 

For example, if demand increases for wool and sheep farmers, raise more animals for wool, there will be a related increase in sheep meat production.

Similarly, if demand increases for X, more of Y will be produced as a by-product.

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