The mean of 5 scores is 7. When an extra score is included, the new mean is 8. What is the extra score?

13

Step-by-step explanation:

Mean of  5 scores = 7

Sum of 5 scores = 7*5 = 35

New mean = 8

Sum of 6 scores = 8 *6 = 48

Extra score = 48 - 35 = 13

statement #3: proof- ang is congruent to ang ecd : angles are congruent.  

step-by-step explanation:

1: the missing angles in statement #3  

a.) acb  

reason- the reason why the answer is acb is because angle ecd and angle acb are both the same size *that's what the word congruent means this is really simple.  

2: the missing word in reason #3  

c.) vertical  

reason- the reason why the answer is vertical is because the angles in that diagram on figure 2 is slanted, which is vertical, and the e and a both lay on vertical lines. along with the other's, but e and a are the 2 main points you want to focus on. and c is kind of like your starting point, because c is for both angles, not just one.  

i hope that was and understanding.

the answer to this is a. a^2 + b^2 = c^2