Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
kcla1996
Group Title
You have a 5question multiplechoice test. Each question has four choices. You don’t know any of the answers. What is the experimental probability that you will guess exactly three out of five questions correctly?
 2 years ago
 2 years ago
kcla1996 Group Title
You have a 5question multiplechoice test. Each question has four choices. You don’t know any of the answers. What is the experimental probability that you will guess exactly three out of five questions correctly?
 2 years ago
 2 years ago

This Question is Closed

CliffSedge Group TitleBest ResponseYou've already chosen the best response.1
To get the experimental probability, you have to run the experiment.
 2 years ago

kcla1996 Group TitleBest ResponseYou've already chosen the best response.0
can i just do it by writing a binomial
 2 years ago

CliffSedge Group TitleBest ResponseYou've already chosen the best response.1
Yes, this is a binomial situation.
 2 years ago

CliffSedge Group TitleBest ResponseYou've already chosen the best response.1
Consider the probability of success for each trial, the number of trials, the number of successes sought, and the number of combinations of getting that many successes.
 2 years ago

kcla1996 Group TitleBest ResponseYou've already chosen the best response.0
10*9/4^3 this is what i got.....
 2 years ago

CliffSedge Group TitleBest ResponseYou've already chosen the best response.1
Mmm, some of those numbers are right, but aren't in the right places...
 2 years ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.0
exactly 3 right out of 5 means 3 right, 2 wrong and \(\dbinom{5}{2}\) ways to do it
 2 years ago

CliffSedge Group TitleBest ResponseYou've already chosen the best response.1
Number of ways to get 3 out of 5 = 5C3 = 5C2 = 10, so the 10 in right.
 2 years ago

CliffSedge Group TitleBest ResponseYou've already chosen the best response.1
... *is right. 3 successes = (.25)^3 with a 25% chance of getting any question correct at random. 2 failures = (.75)^2 for similar reasons as above.
 2 years ago

kcla1996 Group TitleBest ResponseYou've already chosen the best response.0
so can you help me write the answer?
 2 years ago

CliffSedge Group TitleBest ResponseYou've already chosen the best response.1
See http://stattrek.com/probabilitydistributions/binomial.aspx?Tutorial=Stat for derivation of the binomial formula.
 2 years ago

CliffSedge Group TitleBest ResponseYou've already chosen the best response.1
I think you have everything you need; just multiply it all together.
 2 years ago

kcla1996 Group TitleBest ResponseYou've already chosen the best response.0
i really not get it.
 2 years ago

CliffSedge Group TitleBest ResponseYou've already chosen the best response.1
There are ten ways to get 3 out of 5. (use combinations formula 5choose3) To get 3 successes with a 25% chance each, that's 0.25 × 0.25 × 0.25 = (0.25)^3 To also get the 2 failures with a 75% chance: 0.75 × 0.75 = (0.75)^2 Altogether, the probability is 10 × (0.25)^3 ×(0.75)^2.
 2 years ago

kcla1996 Group TitleBest ResponseYou've already chosen the best response.0
is 10 x (.25)^3 x(0.75)^2 the answer
 2 years ago

CliffSedge Group TitleBest ResponseYou've already chosen the best response.1
Makes sense to me. 10 ways to have 3 successes and 2 failures multiplied by the probability of having 3 successes multiplied by the probability of having 2 failures. See also http://stattrek.com/probability/probabilityrules.aspx?Tutorial=Stat
 2 years ago

kcla1996 Group TitleBest ResponseYou've already chosen the best response.0
but is it the answer
 2 years ago

CliffSedge Group TitleBest ResponseYou've already chosen the best response.1
Does it make sense to you? Why do you still have doubts? Follow those links to that website I posted and study until you understand why the probability is computed that way.
 2 years ago
See more questions >>>
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.