chichai_03 said:
At your university, 40% of the undergraduates are from out of state. If you randomly select nine of the undergraduates, what is the probability that
(a) All are from within the state?
(b) All are from out of state?
(c) Exactly four are from within the state?
(d) At least seven are from within the state?
I DO NOT KNOW WHERE TO START!!! I AM STUMPED! PLEASE HELP! THANK YOU IN ADVANCE!
If 40% of the students are "out-of-state" students, what is the probability that a randomly-chosen student is from out-of-state? Wouldn't it be 40/100, or .4?
If you choose, for example, THREE random students, what is the probability that all three are out-of-state students? Wouldn't that be .4*.4*.4, or (0.4)[sup:n8yts9jm]3[/sup:n8yts9jm]?
And if 40% of the students are out-of-state students, what percent of the students are "in-state" students? If a student is either in-state or out-of-state, and 40% are from out of state, then the REST of the students must be in-state students. 100% - 40% = 60%. What is the probability that a randomly-chosen student is an in-state student? Wouldn't that be 60/100, or 0.6?
If you choose FOUR students at random, what would be the probability that they are all in-state-students? Wouldn't that be .6*.6*.6*.6 or (0.6)[sup:n8yts9jm]4[/sup:n8yts9jm]?
Now...any particular student is either "in state" or "out of state"....so the rest of your problems can be solved using the "binomial distribution". I suggest you CAREFULLY read the lesson(s) in your textbook regarding the binomial distribution. You can also refer to numerous online references. This is much too extensive a topic to "teach" here.
If you truly "don't know where to start," it might be a good idea to talk to your instructor about getting some extra help.
