Advertisements
Advertisements
Question
The calculated mean of 50 observations was 80. It was later discovered that observation 19 was recorded by mistake as 91. What was the correct mean?
Advertisements
Solution
Mean = `"The sum of all observations"/"Total number of observations"`
∴ The sum of all observations = Mean x Total number of observations
∴ The sum of 50 observations = 80 x 50
= 4000
Sum of observations after correction = 4000 + 19 – 91
= 3928
∴ Corrected mean = `"Sum of observations after correction"/"Total number of observations"`
= `3928/50`
= 78.56
∴ The corrected mean is 78.56.
APPEARS IN
RELATED QUESTIONS
The mean is one of the numbers in a data.
Solve any two of the following.
In some families in a colony the daily purchase of milk in litre is 1, 3, 2, 2, 4, 1, 2, 2, 1. Find the mean, median and mode of daily purchase of milk.
The mean of 35 observations is 20, out of which mean of first 18 observations is 15 and mean of last 18 observation is 25. Find the 18th observation.
The mean of 5 observations is 50. One of the observations was removed from the data, hence the mean became 45. Find the observation which was removed.
There are 40 students in a class, out of them 15 are boys. The mean of marks obtained by boys is 33 and that for girls is 35. Find out the mean of all students in the class.
Mean of 100 observations is 40. The 9th observation is 30. If this is replaced by 70 keeping all other observations same, find the new mean.
The mean of a, b, c, d and e is 28. If the mean of a, c and e is 24, then mean of b and d is
The mean of 5, 9, x, 17 and 21 is 13, then find the value of x
The mean of a set of numbers is `bar(X)`. If each number is multiplied by z, the mean is
The marks of 14 students in a science test out of 50 are given below. 34, 23, 10, 45, 44, 47, 35, 37, 41, 30, 28, 32, 45, 39 Find the maximum mark obtained
Arithmetic mean of 10 observations was found to be 22. If one more observation 44 was to be added to the data, what would be the new mean?
The mean of first fifteen even numbers is ____________
The average of two numbers are 20. One number is 24, another number is ____________
Arithmetic mean of 15 observations was calculated as 85. In doing so an observation was wrongly taken as 73 for 28. What would be correct mean?
Find the mean of first 10 prime numbers and first 10 composite numbers
Calculate the Mean, Median and Mode of the following data:
5, 10, 10, 12, 13.
Are these three equal?
The following are weights (in kg) of 12 people.
70, 62, 54, 57, 62, 84, 75, 59, 62, 65, 78, 60.
- Find the mean of the weights of the people.
- How many people weigh above the mean weight?
- Find the range of the given data.
Find the mean of first six multiples of 4.
The mean age of 25 teachers in a school is 40 years. A teacher retires at the age of 60 years and a new teacher is appointed in his place. If the mean age of the teachers in this school now is 39 years, then the age (in years) of the newly appointed teacher is ______.
