Question

A coin is tossed three times . then the probability that at least one tail occurs is .
•7/8
•1/8
•3/4
•none of these ​

Answer 1

Answer:

3/4 .....................

Answer 2

Answer:

7/8

Step-by-step explanation:

p = P(tail) = 1/2

q = P(head) = 1 - p = 1/2.

The r.v. X is B(3, 1/2).

Then P(obtaining at least 1 tail in 3 tosses of one coin) = P(X≥1) = P(X = 1) + P(X = 2) + P(X = 3) = 1 - P(X = 0) =

1−(3/0)(1/2)^0(1/2)^3

=1−1×1×(1/2)^3

=1−1/8=7/8