The mean of 7 number is 20. One more number is added to the list, there means 21. Find the added number.
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Answer:
the number is 28
Step-by-step explanation:
mean of 7 numbers is 20.
let the sum of numbers be x.
- mean = sum of all numbers/total numbers
- 20=x/7
therefore, x = 140 (sum of all numbers)
one number is added, let that number be y and mean is changed to 21
- mean = sum of all numbers/total numbers
- 21=(140+y)/8
- 168=140+y
- y=28
therefore the number added is 28.
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