The Brainliest Answer!
expectation is the mean value of what you would get if you did it loads of times. 
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This can be easily explained with an example...
You are really good in maths...and you teacher wants you to score 100 in you exam...
Then you can say that "Your maths teacher EXPECTS you to score 100 in exam".

This word relates a lot when a person desperately want something to happen.
Other Example:
1. I expect to get an increment of 25% by the end of this year
2. My parents have high expectation from me.

it means an attitude of expectancy or hope; anticipation