Answer????
Step-by-step explanation:
 
        
             
        
        
        
Based on the statement below,  if d is the midpoint of the segment AC, the  length of the segment AB  is  4.5cm.
<h3>What is the line segment about?</h3>
in the question given,
AC = 3cm,
Therefore,  AD and DC will be = 1.5cm segments each.  
We are given C as the midpoint of segment DB.
So CB = 1.5cm. 
The representation of the line segment is:
A-----------D------------C-------------B
      1.5           1.5            1.5
Since AD, DC and CB are each 1.5cm segments. Then the equation will be:
= 1.5 + 1.5 + 1.5
= 4.5
Therefore, The length of the segment AB is 4.5cm.
See full question below
If D is the midpoint of the segment AC and C is the midpoint of segment DB , what is the length of the segment AB , if AC = 3 cm.
Learn more about midpoint  from
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Class 2 scored better on average
<h3>How to determine which class scored better on average?</h3>
The averages and the standard deviations are given as:
Class 1
Mean score = 7.8
Standard deviation = 1
Class 2
Mean score = 8.1
Standard deviation = 0.2
As a general rule, the smaller the standard deviation; the better the average
Class 2 has a smaller deviation
Hence, class 2 scored better on average
Read more about standard deviation at:
brainly.com/question/28061243
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Y=1/3x + 2 as the y intercept is 2 and slope is 1/3