A community for students.
Here's the question you clicked on:
 0 viewing
 2 years ago
Wegman claims that their checkout scanners scan correctly 99.8% of the items sold. How many would you expect to buy, on average, to find one that scans incorrectly?
 2 years ago
Wegman claims that their checkout scanners scan correctly 99.8% of the items sold. How many would you expect to buy, on average, to find one that scans incorrectly?

This Question is Closed

Youngster
 2 years ago
Best ResponseYou've already chosen the best response.0i don't think it is that. You have to use the equation\[P(n=r)=nCr*q^{r1}*p^{1}\] It is a binomial model

henpen
 2 years ago
Best ResponseYou've already chosen the best response.0\[P(correct)=p=0.998\]\[P(incorrect)=q=0.002\] We want to find an n so that \[\binom{n}{0}(0.998)^n(0.002)^0<\binom{n}{1}(0.998)^{n1}(0.002)^1\]

Youngster
 2 years ago
Best ResponseYou've already chosen the best response.0wait, what does\[\left(\begin{matrix}n \\ 0\end{matrix}\right)\] mean?

henpen
 2 years ago
Best ResponseYou've already chosen the best response.0It means nC0 \[\binom{n}{0}=1,\binom{n}{1}=1\] \[0.998^n<n0.998^{n1}0.002\] \[\frac{0.998}{0.002}<n\] =499

Youngster
 2 years ago
Best ResponseYou've already chosen the best response.0oh, that makes sense. thanks so much! im going to post another question in a couple of minutes, can u help me with that?

Youngster
 2 years ago
Best ResponseYou've already chosen the best response.0wait, actually ur supposed to use expected value for binormial... i think you get the same answer, but its less confusing. Thanks anyways

kropot72
 2 years ago
Best ResponseYou've already chosen the best response.1Probability of an incorrect scan = 1.000  0.998 = 0.002 Let the expected quantity required to get one incorrect scan = n E(X) = 1 = 0.002n \[n=\frac{1}{0.002}=?\]

Youngster
 2 years ago
Best ResponseYou've already chosen the best response.0@kropot72 500.. so that's the answer?

kropot72
 2 years ago
Best ResponseYou've already chosen the best response.1@Youngster Yes, that's the answer.
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.