"Give at least 3 purposes of commercial radio, using detailed examples."
one reason for commercial radio, of course is to sell a product. It is a good idea for a company to advertise on the radio as it can reach a large number of people as many people listen to the radio since it is free and easily accessed, meaning many people are listening to the product being advertised, giving it a higher chance of selling.
Adding to this, by selecting specific radio stations to broadcast the advert, the company is more likely to reach their target audience, since specific people will listen to specific radio stations.
Another reason for commercial radio is the radio station to make money. Commercial radio stations are funded mainly through advertisements, and so the use of adverts is vital to them otherwise they can not afford to broadcast.
Commercial radio will also buy a particular radio show from other stations in order to save money and increase the number of continuing listeners. For example, Capital FM will often buy the BBC's news stories so they will not have to get their own. This saves money whilst still being able to reach out to the listeners.

