Suppose that you flip a coin 13 times. What is the probability that you achieve at least 5 tails?

Question

anonymous · Answer

thats a binomial probability problem

anonymous · Answer

lol your math teacher must hate you

anonymous · Answer

lol

anonymous · Answer

at least 5 means 5 or 6 or 7 or 8 or 9 or 10 or 11, or 12,or 13

pulsified333 · Answer

No he just gives us insane amounts of homework while the other teachers at the university give like half of what he gives us

anonymous · Answer

you can compute the probability you get 0,1,2,3,4 and subtract that total from 1
it is still going to be a pain

anonymous · Answer

$$P(x=0)=\left(\frac{1}{2}\right)^{13}$$

anonymous · Answer

naw chill just use the formula of sumation

anonymous · Answer

attachment

anonymous · Answer

$$P(x=1)=13\left(\frac{1}{2}\right)^{13}$$

anonymous · Answer

use you calculator to plug it into a summation

pulsified333 · Answer

haven't learned that formula yet

anonymous · Answer

:(

anonymous · Answer

$$P(x=2)=\binom{13}{2}\left(\frac{1}{2}\right)^{13}$$

anonymous · Answer

ok how about the nCr * p^r * q^(n-r) ?

pulsified333 · Answer

yeah i know that

anonymous · Answer

ok now plug it in for the values 1, 2, 3, 4, 5 and add them then subtract that sum from 1

anonymous · Answer

1, 2, 3, 4, 5 being your success rate

anonymous · Answer

cool?

pulsified333 · Answer

yeah

pulsified333 · Answer

but what does (13 2) mean?

anonymous · Answer

13 tries and there are only 2 possible outcomes

pulsified333 · Answer

oh okay

anonymous · Answer

anonymous · Answer

lol

pulsified333 · Answer

thanks :D