Thread: Can someone please check my answers?

I am very strong in math except for in 1 area and that's probabilities. Is there anyone who can please check my answers for me and tell me if I am close or way off base? Thanks in advance!

• Ten percent of adults say oatmeal raisin is their favorite cookie. You randomly select 12 adults and ask each to name his or her favorite cookie.

• The two major criteria for a binomial probability experiment are independence and two possible outcomes. Explain how this experiment meets each these two criteria.

Every answer will either be a success (they like oatmeal raisin cookies) or a failure (they don’t like oatmeal raisin cookies). For independence, the probability of success remains constant for the entire experiment because the answer will either be oatmeal raisin or something else.

• What is the value of :

i.n? __________12____________

ii.p? __________0.1____________

iii.q? _________0.9_____________


c. What is the probability that exactly 3 of the 12 adults surveyed will say their favorite cookie is oatmeal raisin? (You may use the table)



0.085



d. What is the probability that 3 or less adults will say oatmeal raisin is their favorite cookie?
(You may use the table)
0.282+0.377+0.230+0.085 = 0.974

Originally Posted by ezwind72

I am very strong in math except for in 1 area and that's probabilities. Is there anyone who can please check my answers for me and tell me if I am close or way off base? Thanks in advance!

• Ten percent of adults say oatmeal raisin is their favorite cookie. You randomly select 12 adults and ask each to name his or her favorite cookie.

• The two major criteria for a binomial probability experiment are independence and two possible outcomes. Explain how this experiment meets each these two criteria.

Every answer will either be a success (they like oatmeal raisin cookies) or a failure (they don’t like oatmeal raisin cookies). For independence, the probability of success remains constant for the entire experiment because the answer will either be oatmeal raisin or something else.

• What is the value of :

i.n? __________12____________

ii.p? __________0.1____________

iii.q? _________0.9_____________


c. What is the probability that exactly 3 of the 12 adults surveyed will say their favorite cookie is oatmeal raisin? (You may use the table)



0.085



d. What is the probability that 3 or less adults will say oatmeal raisin is their favorite cookie?
(You may use the table)
0.282+0.377+0.230+0.085 = 0.974

In the first part, the reason the trials are independent is that the 12 adults are chosen "at random". The implication is that this means their responses are independent. (You could argue to the contrary. It all depends on what is meant by "at random".)

Your responses on parts c and d are correct.

Cool! Thanks! I understand what you are saying, that makes much more sense than what I read in the book!

In the first part, the reason the trials are independent is that the 12 adults are chosen "at random". The implication is that this means their responses are independent. (You could argue to the contrary. It all depends on what is meant by "at random".)

That's not quite correct. The "at random" I suppose allows for independence, but what they are asking is that an individuals response on one experiment (the experiment being you asking them whether they like Oatmeal raisin or not) is not dependent on the questions you have gotten previously.

Each individual question you are asking is an independent Bernoulli trial with one of two outcomes: a yes or a no (or 0 and 1 if we're setting up random variables). This is the answer the instructor would be looking for, although you certainly can form it as: the probability of success in one trial, is not changed with subsequent trials.