Answer:
c. Lower boundary = 0.50
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of [tex]\pi[/tex], and a confidence level of [tex]1-\alpha[/tex], we have the following confidence interval of proportions.
[tex]\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]
In which
z is the z-score that has a p-value of [tex]1 - \frac{\alpha}{2}[/tex].
An ecologist finds 220 yellow-flowered plants and 180 white-flowered plants.
220 out of 220 + 180 = 400. So
[tex]n = 400, \pi = \frac{220}{400} = 0.55[/tex]
95% confidence level
So [tex]\alpha = 0.05[/tex], z is the value of Z that has a p-value of [tex]1 - \frac{0.05}{2} = 0.975[/tex], so [tex]Z = 1.96[/tex].
The lower limit of this interval is:
[tex]\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.55 - 1.96\sqrt{\frac{0.55*0.45}{400}} = 0.5[/tex]
Thus the correct answer is given by option c.
