Answer:
4x + 6
Step-by-step explanation:
Given
+
Before we can add the fractions we require them to have a common denominator.
Factor the denominator of the first fraction
+
Multiply the numerator / denominator of the second fraction by (x + 2)
= +
← fractions now have a common denominator
Add the numerators leaving the denominators
=
=
= ← simplified sum with numerator 4x + 6
Answer:
The 95% confidence interval for the proportion of students that obtain a letter grade of B or better from this professor is (0.2056, 0.3544). The interpretation is that we are 95% sure that the true proportion of students who obtain a letter grade of B or better from this professor is between 0.2056 and 0.3544.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
For this problem, we have that:
140 students, so
B or better are grades of A or B.
5% earn As, 23% earn Bs, so
95% confidence level
So , z is the value of Z that has a pvalue of
, so
.
The lower limit of this interval is:
The upper limit of this interval is:
The 95% confidence interval for the proportion of students that obtain a letter grade of B or better from this professor is (0.2056, 0.3544). The interpretation is that we are 95% sure that the true proportion of students who obtain a letter grade of B or better from this professor is between 0.2056 and 0.3544.