A poll shows that 70% of all voters approve of the mayor's work. On three separate occasions a pollster selects a voter at random. What is the probabilty that on exactly one of these three occasions the voter approves of the mayor's work?

Could someone please explain this as easy as possible?

Vicky.

Thanks.

If X is the random variable 'number of voters who approve of the mayor' then X ~ Binomial(n = 3, p = 0.7). Calculate Pr(X = 1).

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Thanks for your help. But I don't know what Binomial probability means.
But I could think of three cases

1st person 2nd person 3rd person

1 approve disapprove disapprove

2 disapprove approve disapprove

3 diapprove disapprove approve


Could you please help me a little more?

Vicky.

Calculate the probability of each outcome. Add the results. That's the answer.

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I think I got the answer.

7/10 X 3/10 X 3/10 = 63/1000

3/10 X 7/10 X 3/10 = 63/1000

3/10 X 3/10 X 7/10 = 63/1000

189/1000

Thanks!!!

Correct. (And you're welcome).

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There are two things you should never try to prove: the impossible and the obvious.

The greater danger for most of us lies not in setting our aim too high and falling short; but in setting our aim too low and achieving our mark. (Michelangelo Buonarroti)

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