Answer:
Third option is correct.
Step-by-step explanation:
The given model is
![h(t)=-16t^2-30t+124](https://tex.z-dn.net/?f=h%28t%29%3D-16t%5E2-30t%2B124)
Where, h(t) is heigth of rock after time t (in seconds).
The initial height of rock is 124 ft.
The leading coefficient is negative. It means it is a downward parabola.
First we have to the x-intercepts of the function.
![0=-16t^2-30t+124](https://tex.z-dn.net/?f=0%3D-16t%5E2-30t%2B124)
Using quadratic formula, we get
![t=\frac{-(-30)\pm \sqrt{(-30)^2-4(124)(-16)}}{2(-16)}](https://tex.z-dn.net/?f=t%3D%5Cfrac%7B-%28-30%29%5Cpm%20%5Csqrt%7B%28-30%29%5E2-4%28124%29%28-16%29%7D%7D%7B2%28-16%29%7D)
and ![t=2](https://tex.z-dn.net/?f=t%3D2)
It means rock remains in the air between
.
The value of t can not be negative, therefore rock remains in the air between
.
Third option is correct.
Answer:
4.25
Step-by-step explanation:
Here in this question, we want to calculate the mean absolute deviation of the data.
The first thing we will do here is to calculate the mean;
= (74 + 79 + 76 + 85 + 87 + 83 + 86 + 78)/8 = 81
Now, the next thing to do here is to calculate how far each of the values have deviated from the mean. This can be calculated by subtracting the mean from each individual value;
This is presented in the table on the attachment, please check attachment for this
Afterwards, we find the absolute value of all these subtractions then divide by 8 which is the number of values in the data.
Mean absolute deviation = Sum of all absolute deviations/number of values in dataset