Mean=total/the number of values =>total=mean*the number of values
the total of the first set of 8 numbers is : total=8*8=64
the total of the second set of 12 numbers is: 12m
the total of the 20 numbers is: 64+12m
the mean of the 20 number is: (64+12m)/20=5
solve for m: 64+12m=100
12m=36
m=3
Using derivatives, it is found that:
i) 
ii) 9 m/s.
iii) 
iv) 6 m/s².
v) 1 second.
<h3>What is the role of derivatives in the relation between acceleration, velocity and position?</h3>
- The velocity is the derivative of the position.
- The acceleration is the derivative of the velocity.
In this problem, the position is:

item i:
Velocity is the <u>derivative of the position</u>, hence:

Item ii:

The speed is of 9 m/s.
Item iii:
Derivative of the velocity, hence:

Item iv:

The acceleration is of 6 m/s².
Item v:
t for which a(t) = 0, hence:




Hence 1 second.
You can learn more about derivatives at brainly.com/question/14800626
The answer is 1/2
please see the attached picture for full solution
Hope it helps
I think the answer to your question is
3,942,000