Question

The federal government states that 79% of Canadians are in favour of Canada's ratifying the Kyoto Accord. If this is the true proportion of Albertans favouring ratification, (Input answers to four decimal places)
(a) what is the probability that, in a random sample of 40 Albertans, exactly 24 would support ratification?

(b) what is the probability that at least 24 but no more than 34 would support ratification?

(c) what is the expected number in a sample of 40 Albertans who would oppose ratification?

Answer 1

Given n = 40 and p = 0.79

a) The probability that, in a random sample of 40 Albertans, exactly 24 would support ratification is:

P(X=24) = Binompdf(40, 0.79, 24) = 0.0031

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b) The probability that at least 24 but no more than 34 would support ratification is:

P(24<X<34) = Binomcdf(40, 0.79, 24) - Binomcdf(40, 0.79, 23) = 0.8711

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c) The expected value is:

E(X) = np = 40(0.79) = 31.6