There are three children in a room, ages three, four, and five. If a four-year-old child enters the room the
(a) mean age will stay the same but the variance will increase.
(b) mean age will stay the same but the variance will decrease.
(c) mean age and variance will stay the same.
(d) mean age and variance will increase.
(e) mean age and variance will decrease.
Mean age will stay the same but the variance will decrease.