The brand name of a certain chain of coffee shops has a 46% recognition rate in the town of coffleton. in a random sample of 8 coffleton residents find the probability that exactly 4 of the 8 coffleton residents recognize the brand name.

Respuesta :

This could be solved by using the formula for Repeated Trials Probability:

[tex]Probability=(nCr)( p^{r} )( q^{n-r} )[/tex]

where
nCr is a combination formula: [tex] \frac{n!}{r!(n-r)!} [/tex]
But this can be easily solved using scientific calculator by inputing nCr. 
n is the number of trials or total events (n=8)
r is the number of success trials or success out of the total events (r=4)
p is the probability of the success happening (p=46%)
q is the probability of the fail happening (q = 100-46%=54%)

Substituting,

[tex]Probability=(8C4)( 0.46^{4} )( 0.54^{8-4} )=0.2665[/tex]

Or in percentage form, the probability is 26.65%.