Let’s go step by step to solve this problem.
We are told that:
> “The average of 5 numbers is 12. If one number is removed, the average of the remaining 4 numbers is 10.”
We need to find:
What is the number that was removed?
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Step 1: Understand what “average” means
Average = (Sum of all numbers) ÷ (Number of items)
So if the average of 5 numbers is 12, then:
→ Sum of those 5 numbers = 5 × 12 =
60
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Step 2: After removing one number, we have 4 numbers left
Their average is 10, so:
→ Sum of the remaining 4 numbers = 4 × 10 =
40
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Step 3: Find the removed number
The removed number must be the difference between the original sum and the new sum:
→ Removed number = 60 - 40 =
20
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✔ Let’s double-check:
Original 5 numbers add up to 60.
Remove 20 → left with 40.
Average of 4 numbers: 40 ÷ 4 = 10 → matches the problem!
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Final Answer:
20
Parent Tip: Review the logic above to help your child master the concept of defense mechanisms worksheet substance abuse.
