It was reported that 23% of U. S. adult cellphone owners called a friend for advice about a purchase while in a store. If a sample of 15 U. S adult cellphone owners is selected, what is the probability that 7 called a friend for advice about a purchase while in a store

And using the probability mass function we got:

Step-by-step explanation:

Let X the random variable of interest, on this case we now that:  

The probability mass function for the Binomial distribution is given as:  

Where (nCx) means combinatory and it's given by this formula:  

And we want to find the following probability:

And using the probability mass function we got:

y=mx+b

step-by-step explanation:

m slope, b y-intercept