Question

The mean of 80 observations was found to be 25.If at the time of calculation two items were wrongly taken as 60 and 40 instead of 16 and 4, find the correct mean

Answer 1

Answer:

24

Step-by-step explanation:

mean of 80 observations is 25

sum of 80 observations is 80×25=2000

correcting sum of observations 2000-60-40+16+4

=1920

mean of sum 1920 is 1920/80

that is 24

Answer 2

The correct mean is 24.

Step-by-step explanation:

Since we have given that

Number of observations = 80

Mean = 25

$\bar{x}=\dfrac{\text{Sum of observation}}{\text{Number of observation}}\\\\25=\dfrac{\sum x}{80}\\\\80\times 25=\sum x\\\\2000=\sum x$

According to question, it was mistakenly taken as 60 and 40 instead of 16 and  4.

So, it becomes,

$\sum x -60-40+16+4=2000-100+20=2000-80=1920$

So, the correct mean would be

$\bar{x}=\dfrac{1920}{80}=24$

Hence, the correct mean is 24.

# learn more:

The mean of 80 items is 25. at the time of calculation 2 items are wrongly taken as 16 and 40 instead of taking 16 and 4 are correct.find the correct mean.

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