# A coin is tossed thrice. Find the probability of getting (i) exactly two heads (ii) at least two tails.

Probability is the measurement of chances – the likelihood that an event will occur. If the probability of an event is high, it is more likely that the event will happen. It is measured between 0 and 1, inclusive. So if an event is unlikely to occur, its probability is 0. And 1 indicates the certainty for the occurrence.

Probability is a measure of the likelihood of an event to occur. Many events cannot be predicted with total certainty.

The probability formula is defined as the possibility of an event to happen is equal to the ratio of the number of outcomes and the total number of outcomes.

Probability of event to happen P(E) = Number of favourable outcomes/Total Number of outcomes

Given

A coin is tossed 3 times

Find out

We have to determine the probability of getting

(i) Probability of getting at least two tails

(ii) Probability of getting at least two heads

Solution

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 at least two heads= HHT, HTH, THH

Number of events =n(E)=3

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

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