Mike, whilst walking along Collins Street came across a shop selling the "JOYRIDE" technology based NIKE running shoes considered superior by the world's best athletics.Although Mike already owns four pairs of NIKE runners, he decided to buy the new runners.

Feeling please with himself Mike went to the pub for a beer.It was "Happy hour" at the Pub and the beers were 30 percent cheaper.Mike drank three beers rather than his usual two beers. Using demand and supply graphs illustrate and explain the concepts:

1. Change in quantity demanded
2. Change in demand