I think I could help you
Have fun and feel free to ask me something new.
Or we can prove some properities without calculating by details
The mean will be 5 points higher...so...c would be the answer!
Since x is the number of seconds it took the rock to hit the water, x is the value that we are looking for. When the rock hits the water, it's height is 0, therefore, f(x) = 0. So, we can set the expression on the right equal to 0, and solve for 0. Let's do just that:

We can divide by -16, nothing will happen because 0 divided by anything is 0:

To factor any trinomial in standard form (given below), we must find two numbers that add to "b" and multiply to "c":

So, for this specific question, let's find two numbers that add to -8 and multiply to 9. These are clearly 9 and -1. We can write it in this way now:

Both answers would be valid, but there can't be negative time, so your answer is
"It takes 9 seconds for the rock to reach the water."
For this case, the first thing we must do is define variables.
We have then:
t: the time in minutes
k: the number of kilometers
The relationship between both variables is direct.
Therefore, the function is:

Where, "c" is a constant of proportionality.
To determine "c" we use the following data:
After running for 18 minutes, she completes 2 kilometers.
Substituting values:

Clearing c we have:


Then, the equation is given by:

Answer:
An equation that can be used to represent k, the number of kilometers Julissa runs in t minutes is:
