✔ 最佳答案
H = head and T = tail
P(H) = (1/2)
P(T) = (1/2)
Method 1 :
P(getting 2 H and 1 T from flipping a coin)
= C(3,2) × [P(H)]² × P(T)
= (3!/2!1!) × (1/2)² × (1/2)
= 3/8
Method 2 :
P(getting 2 H and 1 T from flipping a coin)
= P(HHT) + P(HTH) + P(THH)
= (1/2)×(1/2)×(1/2) + (1/2)×(1/2)×(1/2) + (1/2)×(1/2)×(1/2)
= 3/8