Q. 185.0( 2 Votes )

# A coin is tossed thrice and all the eight outcomes are assumed equally likely. In which of the following cases are the following events A and B are independent?

i. A=the first throw results in head, B=the last throw results in tail

ii. A=the number of heads is odd, B=the number of tails is odd

iii. A=the number of heads is two, B=the last throw results in head

Answer :

It is given that the coin is tossed thrice, so the sample space will be,

S={HHH,HHT,HTH,HTT,THH,THT,TTH,TTT}

For independent event, P(A)*P(B)=P(A∩B)

i. A=the first throw results in head, B=the last throw results in tail

A={HHH,HHT,HTH,HTT}

B={HHT,HTT,THT,TTT}

A∩B={HHT,HTT}

Therefore A and B are independent events.

ii. A=the number of heads is odd, B=the number of tails is odd

A={HTT,THT,TTH}

B={HTH,THH,HHT}

A∩B={}=Ø

A and B are not independent

iii. A=the number of heads is two, B=the last throw results in head

A={HHT,HTH,THT}

B={HHH,HTH,THH,TTH}

A∩B={HTH}

Therefore A and B are not independent events.

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