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David
David, Post-Doctoral Degree
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Recent statistics suggest that 15 percent of those who visit

Resolved Question:

Recent statistics suggest that 15 percent of those who visit a retail site on the World Wide Web make a purchase. A retailer wished to verify this claim. To do so, she selected a sample of 16 “hits” to her site and found that 4 has actually made a purchase.
a. What is the likelihood of exactly four purchases?
b. How many purchases should she expect?
c. What is the likelihood that four or more “hits” would result in a purchase?
Submitted: 5 years ago.
Category: Math Homework
Expert:  David replied 5 years ago.

David :

here are the answer:

David :


a) 4C16*0.15^4*0.85^12=0.1311
b) 16*0.15= 2.4
c) 1-0.85^16-16*0.15*0.85^15-120*0.15^2*0.85^14-1820*0.15^4*0.85^12=0.3076

David :

actually

David :

the lasst one

David :

is incorrect

David :

here is the correct answewr:

Customer:

thats not what i got for the last one

David :

1-0.85^16-16*0.15*0.85^15-120*0.15^2*0.85^14=0.4386

David :

o, not really

David :

I messed it up

David :

give me a sec

David :

and I'll post corrcet version

Customer:

ok thank you

David :

here is the correct one:

David :


c) 1-0.85^16-16*0.15*0.85^15-120*0.15^2*0.85^14-560*0.15^3*0.85^13=0.2101

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