Question 1; Niacin is particularly important for men over 50 since it helps them

Question

Question 1;

Niacin is particularly important for men over 50 since it helps them to maintain healthy blood cholesterol levels. A researcher randomly selects 10 men over 50 years old and ascertains whether or not each individual's level of niacin in his bloodstream is high, average, or low.

Does this constitute a binomial experiment?

-Yes

-No, the trials are not identical.   

-No, the requirement that each trial results in either a success or failure is not met.

-No, niacin levels are numerical so the outcome of each trial is not either a success or a failure.

-No, the value of p may not be constant from trial to trial.

Question 2:

When a survey calls residential telephone numbers at random, only 40% of the calls reach a live person. You watch the random dialing machine make 20 calls.

(a) What is the probability that exactly 3 calls reach a person? ____________(Use 3 decimal places.)

(b) What is the probability that 3 or fewer calls reach a person? ____________ (Use 3 decimal places.)

Explanation / Answer

1) we ascertains whether or not each individual's level of niacin in his bloodstream is high, average, or low.

It is not Binomial distribution since the requirement that each trial results in either a success or failure is not met.

2)

Let x follows binomial with n=20 and p=0.4

Then

a) probability that exactly 3 calls reach a person =P(3) =20C3 (0.4)3*(0.6)20-3 =0.012

b) probability that 3 or fewer calls reach a person=P(x<3) =P(0)+P(1)+P(2) =0.004 (Using Binomial Calculator)

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