So, we divide by another 2! to cancel out double counting of two T's. Finally, if we divide all 6 different ways of getting exactly 2 heads (and 2 tails) in 4 flips by all possible outcomes 2 * 2 * 2 * 2 = 16 we would get the probability of exactly 2 heads in 4 flips.
the area for the sand box would be calculated as length × width. since the sandbox is square each side is the same length. the side will be half the number of the area.
