<p>Can someone clarify this for me?</p>
<p>When you're doing probablity story problems involving like "six dice are rolled - what is the probablity of getting at least four fives?" what do you multiply your answer by? I understand that you could get four, five, or six fives and I know how to get the probablities of each of those, but my teacher keeps telling us to multiply the answer... can somebody in pre-calc or stats help me out?</p>
<p>Q(x) = probability of getting x fives</p>
<p>Answer is Q(4) + Q(5) + Q(6)</p>
<p>ya we're not there yet...we just finished laws of cosine, laws of sine, heron's formula etc.......i love probability but i forgot it all so ya....we do probablility really late in our book...its like 10 out of 12 or 13....something like that</p>
<p>thank you - I have to take my final tomorrow :(</p>
<p>Do I have to figure out all the different ways that 4 of one number and 2 different numbers and 5 of one number and 1 other could be arranged and then do a permutation and multiply the answer? Or has my teacher just thouroughly confused me? Aaaaaaaaaaaaaaaaaaaaaaaaaaaah....</p>
<p>Using Boridi's notation, Q(4) = (6 choose 4) * (1/6)^4 * (5/6)^2,
Q(5) = (6 choose 5) * (1/6)^5 * (5/6),
Q(6) = (6 choose 6) * (1/6)^6
and you add them up like he said, recalling that 6 choose 4 =
(6<em>5</em>4*3)/4! = 15 etc.</p>
<p>do u have a ti-83, if so you can look up how to do this on your calculator using binomial theory</p>
<p>This is an AP stats topic generally, however you should be able to pick it up</p>
<p>press 2nd then vars choosing binomialcdf( )</p>
<p>about the calculator - I have a ti-84 silver so I can do the binomial thing, but how do I go about putting it in? My teacher never even mentioned that...</p>