Answer:
$290
Step-by-step explanation:
We are told that 1 out of 5 buyers change to a more expensive sofa than the one in the sale advertisement.
Now we are told that the advertised sofa is $250 and the more expensive sofa is $450.
Thus;
P(x) for expensive sofa = 1/5
P(x) for sofa in sale advertisement = 4/5
Thus, expected value is;
E(X) = (1/5)450 + (4/5)250
E(x) = 90 + 200
E(x) = $290