Answer:
0.667
Step-by-step explanation:
Given that :
Head is twice more likely to occur than a tail.
P(head) = p(H) = 2/3
P(tail) = p(T) = 1/3
If coin is tossed 3 times :
P(H = 0) :
1st toss = tail ;2nd toss = tail ; 3rd toss =. Tail
(1/3) * (1/3) * (1/3) = 1 / 27
P(H= 1)
HTT, THT, TTH
(2/3 * 1/3 * 1/3) + (1/3 * 2/3 * 1/3) + (1/3 * 1/3 *2/3)
= 2/27 + 2 /27 + 2/27
= 6/27 = 2/9
P(H=2)
HHT, HTH, THH
(2/3 * 2/3 * 1/3) + (2/3 * 1/3 * 2/3) + (1/3 * 2/3 * 2/3)
= 4/27 + 4/27 + 4/27
= 12 / 27
= 4 /9
P(H = 3)
HHH
(2/3 * 2/3 * 2/3)
= 8 / 27
X ___ 0 ___ 1 ____ 2 ____ 3
P(x) _ 1/27 _ 2/9 __ 4/9 __ 8/27
E(X) = (0 * (1/27)) + (1 * (2/9)) + (2 * (4/9)) + (3 * (8/27)) = 2
E(X) = 2
Var(X) = Σx²p(x) - E(X)²
= (0^2 * (1/27)) + (1^2 * (2/9)) + (2^2 * (4/9)) + (3^2 * (8/27)) - 2^2
= 4.667 - 4
= 0.667
Hence, Var(x) = 0.667
