We have been given that the standard deviation of a group of 20 scores is 15 and we are asked to find variance.
Since we know variance is square of standard deviation. In order to find out the variance of the given data we have to take the square of 15.

Therefore, our variance is 225.
Answer:
It takes 3 seconds over the interval [0,3]
Step-by-step explanation:
To find when the roller coaster reaches the ground, find when d=0.

To solve divide each term by 16 and factor:

Solve for t by setting each factor to 0.
t-3=0 so t=3
t+3=0 so t=-3
This means the car is in the air from 0 to 3 second.
The answer is Always true. because A is greater than B so put it this way if A=2 and B =1 then 2>1 same goes for C>D so if A+C would have to be greater than B+D for instance 2+2>1+1 or 4>2 so
<span>If A>B and C>D, then A+C>B+D Always true.
</span>