Just Statistics!
Level
pending
The mean of 25 numbers is 36. The mean of the first thirteen numbers is 32 and that of the last 13 numbers is 39,find the 13th number. Consider the numbers are arranged in ascending order always.
The answer is 23.
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1 solution
Sum of 25 no.s=36×25=900
Sum of 1st 13 no.s=32×13=416
Sum of last 13 no.s=39×13=507
Now, sum of last 12 no.s = sum of 25 no.s - sum of 1st 13 no.s = 900 - 416 = 484
Now,13th no. = sum of last 13 no.s - sum of last 12 no.s = 507 - 484 = 23
Ans: 23