On a TV game show, the contestant is asked to select a

Question

door and then is rewarded with the prize behind the door
selected. If the doors can be selected with equal probability,
what is the expected value of the selection if the
three doors have behind them a $40,000 foreign car, a $3
silly straw, and a $50 mathematics textbook?

Answer 1

Each door has a prob of 1/3

expected value
= 1/3( 40000 + 3 + 50 ) = 13351

Answer 2

How did you get this answer I want to make sure im doing this correctly, thank you.

Answer 3

expected return on picking first door
= (1/3)(4000)
expected return on second door
= (1/3)(3)
expected return on third door
= (1/3)50)

so expected return on whole event
= (1/3)(4000) + (1/3)(3) + (1/3)(50)
= (1/3)( 40000 + 3 + 50 ) = 13351 as above