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One coin is tossed 3 times. Find the probability of each event: a) 3 heads b) 3 tails c) tails then heads, then tails

User Christian Dechery
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1 Answer

16 votes
16 votes

Given:

One coin is tossed 3 times.

Required:

We need to find the probability of

a) 3 heads,

b) 3 tails and

c) tails then heads, then tails

Step-by-step explanation:

The sample space for tossing a coin 3 times


S=\lbrace HHH,HTT.HTH.HHT.HTT,THH,TTT.TTH.HHT.TTT\rbrace
n(S)=8

a)

Let A be the event of getting 3 heads.


A=\lbrace HHH\rbrace
n(A)=1

The probability of getting three heads is


P(3\text{ heads\rparen=}(n(A))/(n(S))=(1)/(8)

b)

Let B be the event of getting 3 tails.


B=\lbrace TTT\rbrace
n(B)=1

The probability of getting three tails is


P(3\text{ tails\rparen=}(n(B))/(n(S))=(1)/(8)

c)

Let C be the event of getting tails then heads, then tails


C=\lbrace THT\rbrace
n(C)=1

The probability of getting tails then heads, then tails is


P(\text{ tails then heads, then tails\rparen=}(n(C))/(n(S))=(1)/(8)

Final answer:


P(3\text{ heads\rparen}=(1)/(8)
P(3\text{ tails\rparen}=(1)/(8)
P(\text{ tails then heads, then tails\rparen}=(1)/(8)

User Espen Schulstad
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