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In a bag of 30 chocolates, 12 have vanilla filling and 18 have strawberry filling. Five chocolates are randomly chosen from the bag.
a) What is the probability of obtaining exactly 2 chocolates with strawberry filling?
b) What is the expected number of vanilla filling chocolates?
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(a) P = = = 0.2362 (rounded). ANSWER
(b) Expected value = 0*P(0 vanilla,5 strawberry) + 1*P(1 vanilla,4 strawberry) + 2*P(2 vanilla,3 strawberry) +
+ 3*P(3 vanilla,2 strawberry) + 4*P(4 vanilla,1 strawberry) + 5*P(5 vanilla,0 strawberry) ,
and you can write any probability term in this formula as I did in part (a), and complete calculations on your own.
To facilitate calculations of combination coefficients, I used the COMBIN function of Excel spreadsheet in my computer.
Alternatively, you can use your calculator, which (probably) has similar function.
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Solved, and you got first class instructions to complete the task on your own.