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Connecting the Dots…

Share it out equally

Rain in five months: 90, 110, 100, 130 and 70 mm. A mm, or millimetre, is a tiny length. How wet were the five months? Give one number.

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Five months, five heights: 90, 110, 100, 130, 70 mm.
Step 1 of 2
  1. Five months, five heights: 90, 110, 100, 130, 70 mm.
  2. Move blocks until every stack is 100 mm.

One number for the five months is 100 mm a month.

Add all the readings. Share the total equally. That share is the mean. It is also called the average.

Moving blocks never changes the total. 90 + 110 + 100 + 130 + 70 = 500. There are 5 months, so we need 5 equal shares. Then 500 ÷ 5 = 100 mm.

Sharing equally may not give a whole number. Four crates hold 2, 3, 4 and 6 mangoes. The total is 2 + 3 + 4 + 6 = 15. Then 15 ÷ 4 = 3.75.

Watch out!

No crate holds 3.75 mangoes. That is fine. The mean is the size of one share.

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This track

  1. 0 Start here
  2. 1 One number for the whole lot
  3. 2 Share it out equally
  4. 3 The middle one, once they are in order
  5. 4 When two numbers share the middle
  6. 5 The one that appears most
  7. 6 When one strange value pulls them apart
  8. 7 Which one answers the question
  9. 8 Dots on a number line
  10. 9 How far apart are the ends
  11. 10 Two bars for every item
  12. 11 Checkpoint
  13. 12 The big picture
  14. 13 Track quiz

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