Question

	Too Small	Too Large	Total
Low Income	12	28	40
High Income	30	5	35
Total	42	33	75

a) Find the proprotion of all children that drew the nickel too small

*Assume that this proprotion is true for ALL children in an entire population

b) If 6 children are chosen, find the probability that exactly 2 woould draw the nickel too small

c) If 6 children are chosen at random, find the probability that at least one would draw the nickel too small

d) If 120 children are chosen at random, it would be unusual if more than

I've been struggling with these problems ALL day! 

For the part a I got: 42/75

For part b I got: (42/75)^2*(33/75)^3= 0.0267

for part c I got: (at least one)= 1- (none) which would be: 1-(33/75)^6=.9967

I cannot figure part D out!

Did I answer these correctly? If not was I supposed to use permuations/combinations for these types of questions? HOW do i set up part d?

Any help or explination would be so nice and I would be very grateul!!!!

Answer 1

ref.  https://www.homeworklib.com/question/1500827/the-correct-size-of-a-nickel-is-2121-millimeters