Answer:
4
Step-by-step explanation:
The mean is the average of a data set. It can be found by adding up all of the values in a data set and then dividing it by the number of values in the data set.
The values in this data set;

The number of values in this data set,

Find the mean;


Step-by-step explanation:

Answer:
A
Step-by-step explanation:
I'm not sure but 180° is too much and it ain't anticlockwise
To eliminate x, the coefficients of x's in both equations should be opposite numbers. Since the coefficient of x in the second equation is 3, the coefficient in the first equation should be -3. So she should multiply the first equation by -3.
Answer:
Step-by-step explanation:
This is already factored for us, which is really nice, so now all we need to do is apply the Zero Product Property to the sets of parenthesis and solve for x, which will give us the 2 times that the object is on the ground.
x + 1 = 0 so
x = -1
x - 9 = 0 so
x = 9
We all know that time cannot ever be negative, so the time that the object is on the ground is 9 seconds after it's launched (which was from an initial height of 45 meters).