In tossing three coins at a time, what is the probability of getting at most one head ?

Options

A. `3/8`
B. `7/8`
C. `1/2`
D. `1/8`

Answer

C

Explanation

Possible samples are as follows
{HHH, HTH, HHT, THH, TTH, THT, HTT, TTT}
Let A be the event of getting one head.
Let B be the event of getting no head.
Favourable outcome for
a = {TTH, THT, HTT}
Favourable outcome for
B = {TTT}
Total no. of outcomes = 8
`therefore P(A) = 3/8, P(B) = 1/8`
`therefore` Required probability of getting one head + probability of getting no head
`= P(A) + P(B) = 3/8 + 1/8 = 4/8 = 1/2`