Answer:
Probability to get tails exactly 8 times or exactly 5 times is 0.29
Step-by-step explanation:
No of ways the coins lands tails exactly 8 times
P(8) = 15C8 × [tex]0.5^{8}[/tex] × [tex]0.5^{15-8}[/tex]
No of ways the coin lands tails exactly 5 times
P(5) = 15C5 × [tex]0.5^{5}[/tex] × [tex]0.5^{15-5}[/tex]
Probability to get tails exactly 8 times or 5 times
P(8)+P(5) = 15C8 × [tex]0.5^{15}[/tex] + 15C5 × [tex]0.5^{15}[/tex]
P = [tex]0.5^{15}[/tex] ( 15C8 + 15C5 )
P = [tex]0.5^{15}[/tex] ( ( [tex]\frac{15!}{8!(15-8)!}[/tex] ) + ( [tex]\frac{15!}{5!(15-5)!}[/tex] ) )
P = [tex]0.5^{15}[/tex] ( 6435 + 3003 )
P = [tex]0.5^{15}[/tex] ( 9438)
P = [tex]0.5^{14}[/tex] ( 4719)
P = [tex]\frac{4719}{16384}[/tex]
P = 0.29
