Suppose we have a bag with 10 slips of paper in it. Eight slips have a 3 on them and the other two have a 9 on them. How many 9's do I have to add before the expected value is at least 8?
Write as equation:
3×8+9×2+9x=8(10+x)
42+9x=80+8x
42+x=80
x=38
