the average of 25 results is 18.the average of first 12 of them is 14 and that if last 12 results is 17.fibd the 13th result
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Answered by
4
the result of 13th observation is 78
ggshhs:
how do you get it
first find the sum of 25 observations
next find the sum of 12 observations
next find the sum of last 12 observations
add the sum of first 12 observations and sum of last 12 observations
now subtract that both sums from total sum of 25 observations
u will get the answer
Answered by
15
Solution :
__________
The average of 25 results = 18
So, the total sum of results = 25 x 18 =
450
Now
The average of first 12 results = 14
So, the sum of first 12 results = 12x14 = 168
The average of last 12 results = 17
So, the sum of last 12 results = 17x12 = 204
Total sum of 24 results (12 +12) = 168 + 204 = 372
So, the missing number, means the 13th results is =
(total sum of 25 results) - (total sum of 24 results)
That is, 450 - 372 = 78
So, the 13th result is 78 marks.
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Hint :25 results = (first 12 results) + 13th result + (last 12 results)
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Any problem in understanding, please feel free to ask or discuss in the comment box.
how to get 24
answer is 78 but not 24
if they give all 25 observations and 23 observations and 25th observations then we can find 24th observations
no the total sum of 24
Make it easy now..u write numbers starting from 1 to 25..now strike over the first 12 and also strike over the last 12..u will get only one number which is left..and that is number 13...and see the solution ..and u will understand how we get 78 as the value of the 13th observation.
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