Question

Elly's hot dog emporium is famous for its chilidogs. Some customers order the hot dogs with hot peppers, while many do not care for that added bit of zest.  Elly's latest sales indicate that 30% of the customers ordering her chilidogs order it with hot peppers.  Suppose 18 customers are selected at random, what is the probability that fifteen or more customers will want hot peppers is          

Answer 1

Solution :

x : the customers ordering her chilidogs order it with hot peppers.

n = 18 , p = 30% = 0.30

Using Binomial distribution ,

B(x; n, p) = nCx * px * (1 – p)n – x

Where:
B : Binomial
x = total number of “successes” (pass or fail, heads or tails etc.)
p = probability of a success on an individual trial
n = number of trials

Using Excel Function, BINOMDIST(x,n,p,1)

P( fifteen or more customers will want hot peppers ) = P(x ≥ 15 )

= P(x=15) + P(x=16) + P(x=17) + P(x=18)

= 1 - BINOMDIST(14,18,0.30,1)

= 0.00000436

= 0