Answer:
3718 ways
Step-by-step explanation:
How many ways can a person toss a coin 13 times so that the number of tails is between 7 and 9 inclusive
Probability is the likelihood for an event to occur or not
The formula for a combination is:
n choose r = n! / (r! x (n-r)!)
n=13
r=7 to 9
We are going to add up the cases for 7 through 9:
[tex]^{n } C_{r}[/tex]
[tex]^{13 } C_{7}[/tex]+[tex]^{13 } C_{8}[/tex]+[tex]^{13 } C_{9}[/tex]
[tex]\frac{n!}{r!(n-r)!}[/tex]
[tex]\frac{13!}{7!(13-7)!}[/tex]+[tex]\frac{13!}{8!(13-8)!}[/tex]+[tex]\frac{13!}{9!(13-9)!}[/tex]
1716+1287+715
3718 ways
