Lesson eLearning

There were 10 birds on a tree. Every hour for 3 hours, 2 birds fly away. Then 5 birds arrive. Then 4 birds fly away. How many birds remain on the tree?

hard 3 marks Class 2 · Mathematics · Birds Come Birds Go
Answer
5

The correct answer is 5 — Thus, 5 birds remain.

Step-by-step solution

  1. Start with 10 birds.
  2. Subtract 2 birds that fly away each hour for 3 hours: 10 – 2 – 2 – 2 = 4 birds left.
  3. Add the 5 birds that arrive: 4 + 5 = 9 birds.
  4. Subtract the 4 birds that fly away: 9 – 4 = 5 birds.
  5. Thus, 5 birds remain.
Common mistake: Not accounting for all hours of bird departures

Concept tested: Repeated subtraction and addition

Published · How this solution was prepared and checked

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