Answer:
The upper bound is 399.5
Step-by-step explanation:
Let's start by calculating the mean value of the distribution as the addition of all values given divided by 12:
Average = 289.75.
If the standard deviation is 56, then the upper bound in 95% the confidence interval for the mean price of the phones is going to be given by the mean value added to 56 times 1.96 (since 95% of the population is withing 1.96 times the standard deviation)
That is: 289.75 + 56 * 1.96 = 399.51
which rounded to one decimal place gives: 399.5
To find the factor a a polynomial from its roots, we are going to seat each one of the roots equal to

, and then we are going to factor backwards.
We know for our problem that one of the roots of our polynomial is -3, so lets set -3 equal to

and factor backwards:



is a factor of our polynomial.
We also know that another root of our polynomial is

, so lets set

equal to

and factor backwards:




(

is a factor of our polynomial.
We can conclude that there is no correct answer in your given choices.
Use Desmos insert y=0.4x into the calculator
Answer:
The total would be 300
Step-by-step explanation:
310
-10
-----
300