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Suppose I have an urn full of balls.10 balls are balck, 2 are blue,2 are red,1 is green. I reach into the urn and pull out a ball and record the colour. I then put it back in the urn. If i do this 10 times calculate
a) the probability I obtain exact 4 black balls
b) The probablility I obtain less than 2 red balls

For clarity we are putting the balls back into the urn after the colour is recorded.

Respuesta :

madethisfortwitch1

Answer:

Step-by-step explanation:

Assuming that each draw is independent of the last and that each ball is equally likely to be selected makes this a binomial distribution

a.) first find the probability of selecting a black ball, 2/10 or .2

[tex]{10\choose{4}}.2^4*.8^6=.08808384[/tex]

b.) Probability of slecting a red ball: 1/10 or .1

Less than 2 is X=0 + X=1

[tex]{10\choose0}*.2^0*.8^{10}+{10\choose1}*.2*.8^9=.3758096384[/tex]

i will leave you to do the rounding