Home
Class 12
MATHS
The mean and S.D. of 20 items were found...

The mean and S.D. of 20 items were found to be 12 and 6 respectively. On checking it was discovered that items which should correctly read as 11 and 21 had been wrongly taken as 15 nd 27 respectively. Find the correct values of mean and S.D.

Text Solution

Verified by Experts

The correct Answer is:
`sqrt(160.4-132.25)=sqrt(28.15)=5.3` (approx.).
Promotional Banner

Topper's Solved these Questions

  • MEASURES OF DISPERSION

    CHHAYA PUBLICATION|Exercise Exercise 3 (MCQ)|5 Videos

  • MEASURES OF DISPERSION

    CHHAYA PUBLICATION|Exercise Exercise 3 Very Short answer type|26 Videos

  • Measures of Central Tendency

    CHHAYA PUBLICATION|Exercise Exercise 2 C Very short answer type question|18 Videos

  • MEASURMENT OF TRIGONOMETRICAL ANGLES

    CHHAYA PUBLICATION|Exercise Sample Questions for Competitive Exams (Assertion -Reason Type)|2 Videos

Similar Questions

Explore conceptually related problems

The mean and SD of the scoreing marks of 100 students are 40 and 5.1 resp. on checking it was discovered that the score which should correctly read as 40 had been wrongly taken as 50. Find the correct values of mean and SD

The mean and SD of 20 items were found to be 12.5 and 2.1 resp.After that,one item of 23 being added: find the AM and SD of 21 items

Mean of 100 items is 49. It was discovered that three items which should have been 60, 70,80 were wrongly read as 40, 20, 50 respectively. The correct mean is. (a) 48 (b) 82 1/2 (c) 50 (d) 80

For a group of 200 candidates the mean and S.D. were found to be 40 and 15 respectively. Later on it was found that the score 43 was misread as 34. Find the correct mean and correct S.D.

The mean and standard deviation of a group of 100 observations were found to be 20 and 3, respectively. Later on it was found that three observations were incorrect, which were recorded as 21, 21 and 18. Find the mean and standard deviation if the incorrect observations are omitted.

For a group of 200 students the mean and S.D. of marks obtained by them were found to be 40 and 15 respectively. Later on, it was found that the score 23 was misread as 32. Find the correct mean and correct S.D.

For a group of 200 students the mean and S.D of marks obtained by them were found to be 40 and 15 respectively.Later on,it was found that the score 23 was misread as 32.Find the correct mean and correct S.D

The mean and the standard deviation of a characteristic of 100 items were found to be 60 and 10 respectively. At the time of calculations, two items were wrongly take as 5 and 45 instead of 30 and 20. Calculate the corrected mean and corrected standard deviation.

The mean and S.D. of sample of size 10 were found to be 9.5 and 2.5 respectively. Later on an additional observation became available. This was 15 and was included in the original sample. Find the mean and S.D. of the 11 observations.