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put this solution on YOUR website!To find the average of six numbers you need to add them together and divide by six. This problem tells us five of the the numbers and we need to figure out the sixth number so the resulting average will be 7.55.
So first lets add the five scores we are given:
7.2 + 7.3 + 7.7 + 7.8 + 7.5 = 37.5
Lets call the sixth score x and write an equation based on the given information.

now we can solve for x
first multiply both sides by 6

next subtract 37.5 from both sides
Answer: Dora needs a 7.8 from the sixth judge