I need help trying to find the probability of an answer can you help me. the question is. selecting a committee. a parent-teacher committee consisting of 4 people is to be formed from 20 parents ans 5 teachers. find the probability that the committee will consist of these people.( all teachers)b( 2 teachers and 2 parents)c ( all parents) d (1 teacher and 3 parents). i need to know which formula to use and how to set it up.
Good hint, Ultraglide. I am not very good with probabilities and I stumbled when I tried to help with this question. I see that reather answered "6" to your question "How many committess of four can be formed from 25 people". Is reather correct? I don't think so. Aren't you supposed to use the combination formula nCr = n!/[r!(n-r!)] ? If so, then the answer to your question "How many committess of four can be formed from 25 people" is 25C4 and that is 25*24*23*22*21*20*19*18*17*16*15*14*13*12*11*10*9*8*7*6*5*4*3*2*1 (4*3*2*1)(21*20*19*18*17*16*15*14*13*12*11*10*9*8*7*6*5*4*3*2*1) and that reduces to 25*24*23*22) 4*3*2*1 which is 12650. And for your second hint "How many committees of four can be formed from five teachers?", that would be 5C4 = 5 So the answer to the original question of what the probability of the committee having all teachers is 5/12650 = 1/2530 isn't it?
How many ways can we choose two teachers? Now FOR EACH OF THESE WAYS we can choose two parents. This means that we find the product of these two cases to find the number of committees with two of each.
Thanks. That makes sense. It is all starting to come back to me. 20 years since taking a probability course takes its toll! I got an A in the course but I didn't retain anything after the course was over!
We all have our areas of expertise. The capitalized part was how my high school teacher emphasized the product. When I responded to the linear transformation in another section, I had to pull out my old text. I had forgotten the definition even though I taught it for many years.
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