20 percent of all undergraduates at a university are chemistry majors. In a random sample of 7 students, find the probability that exactly 3 are chemistry majors.

Question

20 percent of all undergraduates at a university are chemistry majors.  In a random sample of 7 students, find the probability that exactly 3 are chemistry majors.

aaronq · Answer

Use the binomial distribution

anonymous · Answer

would it be binompdf in the calc? @aaronq

aaronq · Answer

i think so, pdf = probability distribution function

aaronq · Answer

though i've never used a calc like that

anonymous · Answer

hmm ive used that on a ti 84 befoer but idk if its the right answer i just got

aaronq · Answer

hm check the answers in the back of the book?

anonymous · Answer

online class :/

aaronq · Answer

hmmm, id say work it out manually, it's pretty easy

anonymous · Answer

could you show me the formula for that?

aaronq · Answer

look here http://www.statisticshowto.com/binomial-distribution-formula/ If you want plug your numbers in and post it. i'll take a look at it

anonymous · Answer

.1147?

kropot72 · Answer

$$\large P(3\ Chem\ majors)=\frac{7!}{3!4!}\times0.2^{3}\times0.8^{4}=you\ can\ calculate$$

kropot72 · Answer

You are correct.

anonymous · Answer

sweet thank you!

kropot72 · Answer

you're welcome :)

aaronq · Answer

Oh damn, sorry i didn't see you replied, i'm not getting notifications! You've got good help anyway

anonymous · Answer

its okay thanks too! @aaronq

aaronq · Answer

np!