Question

The mean of 25 observations is 26. Out of these observations if the mean of first 13 observations is 22 and that of the last 13 observations is 30, the 13th observation is

Answer 1

Answer:

26

Step-by-step explanation:

first 12 +13th observation = 13*22 = 286

last 13 observations = 13*30 =390

sum of 25 observations = 26*25 = 650

13th observation= (286+390)-650

=676-650

=26

Answer 2

Given : The mean of 25 observations is 26.

Out of these observations

the mean of first 13 observations is 22 and

that of the last 13 observations is 30,  

To Find :   13th observation  

Solution:

The mean of 25 observations is 26.

Sum of 25 observations = 25 * 26  = 650

mean of first 13 observations is 22

Sum of first 13 observations = 22 * 13  = 286

mean of las 13 observations is 30

Sum of last 13 observations = 30 * 13  = 390

Sum of first 13 observations + sum of last 13 observations

= Sum of all 25 observations + 13th observation  

= 650 +   13th observation  

650 +   13th observation    = 286 + 390

=>  13th observation    = 26

Hence 13th observation  is 26

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