Answer:
Option C.
Step-by-step explanation:
we have
-----> equation A
-----> equation B
Solve the system of equations by graphing
Remember that the solution of the system of equations is the intersection point both graphs
The intersection point is (1,3)
see the attached figure
therefore
The solution of the system of equations is
Find the difference
Answer:
The margin of error for the true mean number of hours a teenager spends on their phone is of 0.4 hours a day.
Step-by-step explanation:
We have the standard deviation of the saple, 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 = 50 - 1 = 49
95% confidence interval
Now, we have to find a value of T, which is found looking at the t table, with 49 degrees of freedom(y-axis) and a confidence level of . So we have T = 2
The margin of error is:
In which s is the standard deviation of the sample and n is the size of the sample.
The margin of error for the true mean number of hours a teenager spends on their phone is of 0.4 hours a day.
