Can someone help me with these?

1. In a certain college, 33% of the physics majors belong to ethnic minorities. Find the probability of the event from a random sample of 10 students who are physics majors. Seven or more belong to an ethnic minority.


a- 0.0028 b-0.0032 c-0.0185 d-0.0154





2. The probability that a radish seed will germinate is .7. The gardener plants 20 seeds and she harvests 16 radishes.


a-0.068 b-0.571 c-0.130 d-0.075





3. If 3 balls are drawn from a bag containing 3 red and 4 blue balls, what is the expected number of red balls in the sample?


a-1.29 b-1.39 c-1.54 d-0.89

Can someone help me with these?
ok i can only help you on the first 2


do you have a graphing calculator?


if not that sucks...


ok i am using a TI-84 texas intruments but i dont know if that matters


ok press 2nd-VARS wich is distr


then go to binompdf


type in 10,.33,7 and it will give you .15


same for the other one type in 20,.7,16


and you get .13


what the calculator is doing is (10c1)(.33^1)(.67^10)+(10c2)(.33^2)(.67^... and so on till it gets to seven


i know for sure that the anwser to 3 is a 1.29 but i dont know how to get it i just know my friend took that quiz and that was the anwser...


if you got any questions i will try to help just emai me
Reply:1 and 2 are examples of finding probabilities from a binomial distribution. The first has n = 10, r = 7 and p = 0.33.


The second has n = 20, r = 16, p = 0.7


Look up formula for binomial probabilities and use it. The only one that might have a different letter used is r.





3. This is a badly worded question. It could be binomial again IF the balls are put back between being taken. If so then you don't have to work out all the probabilities. The mean of a binomial is n*p.


If the balls are not replaced it is quite a bit harder to do.


Since the others were binomial questions then I suspect that this was supposed to be as well, especially as the answer would be very close to one of those given.

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