Mikey has ten marbles in a bag with the number 5 on 8 faces and the number 3 on 2 faces. What is the expected value of the number present when one marble is selected from the bag
The wording is kind of weird... I'm going to assume you mean "what is the expected number on the marble when one is selected from the bag"
There are 10 marbles. 8/10 have the number '5' on them and 2/10 have the number '3' on them. This means it's most likely that the number on the marble is 5 when drawn from the bag.