Answer:
5r + 2
Step-by-step explanation:
9r-5r+2+r=5r+2
\mathrm{Group\:like\:terms}
=9r-5r+r+2
\mathrm{Add\:similar\:elements:}\:9r-5r+r=5r
=5r+2
Answer:
C. ± 2.326 years.
Step-by-step explanation:
We have the standard deviation for the sample. So we use the t-distribution to solve this question.
We have that to find our 
level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of 
.
So it is z with a pvalue of 
, so ![z = 2.326/tex]Now, find the width of the interval[tex]W = z*\frac{\sigma}{\sqrt{n}}](https://tex.z-dn.net/?f=z%20%3D%202.326%2Ftex%5D%3C%2Fp%3E%3Cp%3E%3Cstrong%3ENow%3C%2Fstrong%3E%2C%20find%20the%20width%20of%20the%20interval%3C%2Fp%3E%3Cp%3E%5Btex%5DW%20%3D%20z%2A%5Cfrac%7B%5Csigma%7D%7B%5Csqrt%7Bn%7D%7D)
In which 
is the standard deviation of the population and n is the size of the sample.
In this question:
So
The correct answer is:
C. ± 2.326 years.
The correct answer to this problem is the third statement which is "Alexia completed 20 math problems and 10 science problem". The following conditions are stated in the problem:
Alexia can answer 3 minutes on each math problem
Alexia can answer 4 minutes on each science problem
She worked more than 60 minutes
We have the inequality 3x + 4y > 60 where x represents the total number of math problem while y represents the total number of the science problem.
in our answer, we have x=20and y=10
3*20 + 4*10 > 60
60 + 40 > 60
100 > 60
Therefore, our answer is correct.
