Answer:
The 90% confidence interval for the mean test score is between 77.29 and 85.71.
Step-by-step explanation:
We have the standard deviation for the sample, so we use the t-distribution to solve this question.
The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So
df = 25 - 1 = 24
90% confidence interval
Now, we have to find a value of T, which is found looking at the t table, with 24 degrees of freedom(y-axis) and a confidence level of 
. So we have T = 2.064
The margin of error is:
In which s is the standard deviation of the sample and n is the size of the sample.
The lower end of the interval is the sample mean subtracted by M. So it is 81.5 - 4.21 = 77.29
The upper end of the interval is the sample mean added to M. So it is 81.5 + 4.21 = 85.71.
The 90% confidence interval for the mean test score is between 77.29 and 85.71.
Answer:f(x) has three real roots
Step-by-step explanation:
Answer: last week he made $630
Step-by-step explanation:
14% of 4500 is 630
Answer with Explanation:
If a consistent system has an infinite number of solutions, it is dependent . When you graph the equations, both equations represent the same line.
If a system has no solution, it is said to be inconsistent . Represent parallel lines.
1) 8x + y + 4 = 0
y = -8x - 4
If we solve equation 8x + y + 4 = 0 for y, we get
y = -8x -4
So, both equations are same. That means both lines are same. So infinite many solutions.
System is consistent
2) Both line slope are same and parallel to each other.
So, no solution
System is inconsistent.
3) Both equation represent the same line. So, infinite many solution.
System is consistent.
4) Both lines are intersect at a point.
Intersection point is (7,0).
5) Both lines are parallel. So, no solution.
System is inconsistent.
