Answer :

Let S be the sample space.

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

(i) Let A be the event of getting 3 heads

A = {HHH}

Required probability = P(A)

= =

(ii) Let A be the event of getting 2 heads

A = {HHT, HTH, THH}

No. of favourable outcomes = 3

P(A) =

(iii) Let A be the event of getting alteast 2 heads

A = {HHH, HHT, HTH, THH}

No. of favourable outcomes = 4

P(A) = =

(iv) Let A be the event of getting at most 2 heads.

A = {HHT, HTH, THH, HTT, THT, TTH, TTT}

No. of favourable outcomes = 7

Probability (at most 2 heads) =

(v) Let A be the event of getting no head

A = {TTT}

No. of favourable outcome = 1

Probability (three tails) =

(vi) Let A be the event of getting 3 tails

A = {TTT}

No. of favourable outcome = 1

Probability (three tails) =

(vii) Let A be the event of getting exactly two tails

A = {HTT, THT, TTH}

No. of favourable outcomes = 3

Probability(exactly two tails) =

(viii) Let A be the event of getting no tail

A = {HHH}

No. of favourable outcome = 1

Probability (no tail) =

(ix) Let A be the event of getting at most two tails

A = {HHT, HTH, THH, HTT, THT, TTH, HHH}

No. of favourable outcomes = 7

Probability (at most two tails) = .

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