Explanation
In this sample, people elect to participate or self-select to do the survey. Often, these folks have a strong interest in the main topic of the survey.
In essence, they volunteer to inform the trucking company about the activities of their drivers. That makes this a voluntary sample.
Answer: Voluntary Sampling Method
P(defective) = 3/12 = 1/4
P(good) = 1 - 1/4 = 3/4



The probability that at least 2 units are good is given by:
P(2 good) + P(3 good) + P(4 good) = 0.211 + 0.422 + 0.316 = 0.949.
The two lines coincide. The two equations have the same slope and intercept. If you multiply the second equation by 3, you’ll get the first equation.
Answer:
a) Sample correlation coefficient, r = 0.7411
bi) test statistic, t = 4.102
bii) P-value = 0.000736
Step-by-step explanation:
a) The formula for the sample correlation coefficient is given by the formula:



r = 0.7511
b)
i) formula for the test statistic is given by the formula:

sample size, n = 4

t = 4.102
ii) Degree of freedom, df = n -2
df = 14 -2
df = 12
The P-value is calculate from the degree of freedom and the test statistic using excel
P-value =(=TDIST(t,df,tail))
P-value = (=TDIST(4.1,12,1)
P-value = 0.000736
4 with an exponent of 7 is like saying 4*4*4*4*4*4*4
7 with an exponent of 4 is like saying 7*7*7*7