![{\large{\textsf{\textbf{\underline{\underline{Given :}}}}}}](https://tex.z-dn.net/?f=%7B%5Clarge%7B%5Ctextsf%7B%5Ctextbf%7B%5Cunderline%7B%5Cunderline%7BGiven%20%3A%7D%7D%7D%7D%7D%7D%20)
‣ A coin is tossed three times.
![{\large{\textsf{\textbf{\underline{\underline{To \: Find :}}}}}}](https://tex.z-dn.net/?f=%20%7B%5Clarge%7B%5Ctextsf%7B%5Ctextbf%7B%5Cunderline%7B%5Cunderline%7BTo%20%5C%3A%20Find%20%3A%7D%7D%7D%7D%7D%7D%20)
‣ The probability of getting,
1) Exactly 3 tails
2) At most 2 heads
3) At least 2 tails
4) Exactly 2 heads
5) Exactly 3 heads
![{\large{\textsf{\textbf{\underline{\underline{Using \: Formula :}}}}}}](https://tex.z-dn.net/?f=%20%7B%5Clarge%7B%5Ctextsf%7B%5Ctextbf%7B%5Cunderline%7B%5Cunderline%7BUsing%20%5C%3A%20Formula%20%3A%7D%7D%7D%7D%7D%7D%20)
![\star \: \tt P(E)= {\underline{\boxed{\sf{\red{ \dfrac{ Favourable \: outcomes }{Total \: outcomes} }}}}}](https://tex.z-dn.net/?f=%5Cstar%20%5C%3A%20%5Ctt%20%20P%28E%29%3D%20%7B%5Cunderline%7B%5Cboxed%7B%5Csf%7B%5Cred%7B%20%20%5Cdfrac%7B%20Favourable%20%5C%3A%20%20outcomes%20%7D%7BTotal%20%5C%3A%20%20outcomes%7D%20%20%7D%7D%7D%7D%7D)
![{\large{\textsf{\textbf{\underline{\underline{Solution :}}}}}}](https://tex.z-dn.net/?f=%20%20%7B%5Clarge%7B%5Ctextsf%7B%5Ctextbf%7B%5Cunderline%7B%5Cunderline%7BSolution%20%3A%7D%7D%7D%7D%7D%7D%20)
★ When three coins are tossed,
then the sample space = {HHH, HHT, THH, TTH, HTH, HTT, THT, TTT}
[here H denotes head and T denotes tail]
⇒Total number of outcomes
= 8
<u>1) Exactly 3 tails </u>
Here
• Favourable outcomes = {HHH} = 1
• Total outcomes = 8
![\therefore \sf Probability_{(exactly \: 3 \: tails)} = \red{ \dfrac{1}{8}}](https://tex.z-dn.net/?f=%20%5Ctherefore%20%20%5Csf%20Probability_%7B%28exactly%20%20%5C%3A%203%20%5C%3A%20%20tails%29%7D%20%20%3D%20%20%5Cred%7B%20%5Cdfrac%7B1%7D%7B8%7D%7D%20)
<u>2) At most 2 heads</u>
[It means there can be two or one or no heads]
Here
• Favourable outcomes = {HHT, THH, HTH, TTH, HTT, THT, TTT} = 7
• Total outcomes = 8
![\therefore \sf Probability_{(at \: most \: 2 \: heads)} = \green{ \dfrac{7}{8}}](https://tex.z-dn.net/?f=%20%5Ctherefore%20%20%5Csf%20Probability_%7B%28at%20%5C%3A%20most%20%20%5C%3A%202%20%5C%3A%20%20heads%29%7D%20%20%3D%20%20%5Cgreen%7B%20%5Cdfrac%7B7%7D%7B8%7D%7D%20)
<u>3) At least 2 tails </u>
[It means there can be two or more tails]
Here
• Favourable outcomes = {TTH, TTT, HTT, THT} = 4
• Total outcomes = 8
![\longrightarrow \sf Probability_{(at \: least \: 2 \: tails)} = \dfrac{4}{8}](https://tex.z-dn.net/?f=%20%20%5Clongrightarrow%20%20%20%5Csf%20Probability_%7B%28at%20%5C%3A%20least%20%5C%3A%202%20%5C%3A%20%20tails%29%7D%20%20%3D%20%20%5Cdfrac%7B4%7D%7B8%7D)
![\therefore \sf Probability_{(at \: least \: 2 \: tails)} = \orange{\dfrac{1}{2}}](https://tex.z-dn.net/?f=%20%20%5Ctherefore%20%20%5Csf%20Probability_%7B%28at%20%5C%3A%20least%20%5C%3A%202%20%5C%3A%20%20tails%29%7D%20%20%3D%20%20%20%5Corange%7B%5Cdfrac%7B1%7D%7B2%7D%7D)
<u>4) Exactly 2 heads </u>
Here
• Favourable outcomes = {HTH, THH, HHT } = 3
• Total outcomes = 8
![\therefore \sf Probability_{(exactly \: 2 \: heads)} = \pink{ \dfrac{3}{8}}](https://tex.z-dn.net/?f=%20%5Ctherefore%20%20%5Csf%20Probability_%7B%28exactly%20%5C%3A%202%20%5C%3A%20%20heads%29%7D%20%20%3D%20%20%5Cpink%7B%20%5Cdfrac%7B3%7D%7B8%7D%7D%20)
<u>5) Exactly 3 heads</u>
Here
• Favourable outcomes = {HHH} = 1
• Total outcomes = 8
![\therefore \sf Probability_{(exactly \: 3 \: heads)} = \purple{ \dfrac{1}{8}}](https://tex.z-dn.net/?f=%5Ctherefore%20%20%5Csf%20Probability_%7B%28exactly%20%5C%3A%203%20%5C%3A%20%20heads%29%7D%20%20%3D%20%20%5Cpurple%7B%20%5Cdfrac%7B1%7D%7B8%7D%7D%20)
![\rule{280pt}{2pt}](https://tex.z-dn.net/?f=%5Crule%7B280pt%7D%7B2pt%7D)