Advertisements
Advertisements
Question
The mean of 200 observations is 20. It is found that the value of 180 is wrongly copied as 280. Find the actual mean.
Advertisements
Solution
Since mean of 200 observations = 20
⇒ Sum of 200 observations
= 200 x 20
= 4000
⇒ Incorrect sum = 4000
∴ Correct sum
= Incorrect sum - Incorrect value + Correct value
= 4000 - 280 + 180
= 3900
∴ Correct mean
= `"Correct sum"/"Total number of observations"`
= `(3900)/(200)`
= 19.5.
APPEARS IN
RELATED QUESTIONS
The mean of 15 observations is 32. Find the resulting mean, if each observation is: Multiplied by 2
The mean of 15 observations is 32. Find the resulting mean, if the observation is: Increased by 60%
Find the median of: 25, 16, 26, 16, 32, 31, 19, 28 and 35
The mean of 18, 24, 15, 2x + 1 and 12 is 21. Find the value of x.
The average of n numbers x1, x2, x3 ….. xn is A. If x1 is replaced by ( x+ α )x1, x2, is replaced by ( x+ α )x2 and so on.
Find the new average.
The mean of x, x + 2, x + 4, x + 6 and x + 8 is 11, find the mean of the first three observations.
For the set of numbers given below, find mean: 3, 0, 5, 2, 6, 2
Calculate man of the following: 4, 6, 6, 6, 7, 7, 7, 7, 8, 8, 9, 9, 11, 3
In History project, marks out of 20 were awarded to 8 students. The marks were as shown below:
14, 16, 18, 14, 16, 14, 12, 16
Find the mean marks.
The mean of 16 natural numbers is 48. Find the resulting mean, if each of the number is divided by 0.25
