Average of 21 results is 20 the average of first 10 is 14 and that of the last 10 is 20 what is the average of 11th one?
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Average of 21 results is 20 the average of first 10 is 14 and that of the last 10 is 20 what is the average of 11th one?
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Answer:
Step-by-step explanation:
An average of a group of numbers is of last addition of those numbers divided by number of those numbers
Given: the average of 21 numbers Is 20
So the sum of 21 numbers is 21x20
Which equals 420
Also Given: the average of first 10 number is 24
So the sum of first 10 number is 24x10
Which equals 240
Lastly: the average of last 10 is 14
So sum Is 140
Now sum of all number is 420
And sum of first 10 and last 10 number is 240 and 140 respectively
So 240+140+x=420
Where x is the 11th number
380+x=420
X=40.
Hope it helps you.