Answers

1. Answer:

   the fifth book weighs 1200g

   Step-by-step explanation:

   (400+600+800+1000+x)/5=800 =>

   (2800+x)/5=800 =>

   x=(800×5)-2800=>

   x=4000-2800=>

   x=1200

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2. Answer:

   It appears that the books have a scale factor for each one, meaning that the 5th book would be 1200g.

   To check this regarding the average weight, add the weight of all 5 books together and divide by 5.

   (400 + 600 + 800 + 1000 + 1200) / 5 = 800

   Reply