1.

The mean of 7 number is 20. One more number is added to the list, there means 21. Find the added number.

Answer»

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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