Question

A coin is tossed thrice. Find the probability of getting

(i) exactly two heads.

(ii) at least two tails.

Answer 1

Sample space for tossing 3 coins: {HHH, HTH,THH,TTH, HHT, HTT,THT,TTT}

(i) Probability of getting at least two tails 

Probability of getting at least two tails is:

P(A)=P(getting two tails)+P(getting 3 tails)

= 3/8 + 1/8

= 4/8

= 1/2

Therefore, the probability of getting at least 2 tails if you flip a coin 3 times is 1/2.

(ii)Probability of getting exactly two heads= { HHT, HTH, THH }

Number of events =n(E)=3

Probability of events =P(E)=3/8

 

 

Probability of getting exactly 2 heads = 3/8

Probability of getting atleast 2 tails = 1/2