I've just finished my maths A-Level (I'm British) and one of the topics we covered was the Expected Value of a random variable. I was wondering if this was applicable to sports betting. For example:

Odds my sports team will win are 4:1 against.

Probability will win: 1/5, return of a £1 bet is 5

Probability will lose: 4/5, return of a £1 bet is -1

Expected value is: 0.2

Is this approch applicable?