Advertisements
Advertisements
Question
The mean of 200 items was 50. Later on, it was discovered that two items were misread as 92 and 8 instead of 192 and 88.
Find the correct mean.
Advertisements
Solution
Given that the mean of 200 items was 50.
Mean = `sum_x/n`
⇒ 50 = `sum_x/200`
⇒ x = 10,000
Incorrect value of `sum x`= 10,000
correct value of
`sumx` = 10,000 - ( 92 + 8 ) + ( 192 + 88 )
= 10,000 - 100 + 280
= 10,180
Correct mean
= `("correct value of" sumx")/n`
= `10180/200`
= 50.9
APPEARS IN
RELATED QUESTIONS
Find the mean of the first six natural numbers.
In a series of tests, A appeared for 8 tests. Each test was marked out of 30 and averages 25. However, while checking his files, A could only find 7 of the 8 tests. For these, he scored 29, 26, 18, 20, 27, 24 and 29.
Determine how many marks he scored for the eighth test.
The mean marks (out of 100) of boys and girls in an examination are 70 and 73 respectively. If the mean marks of all the students in that examination are 71,
find the ratio of the number of boys to the number of girls.
If different values of variable x are 9.8, 5.4, 3.7, 1.7, 1.8, 2.6, 2.8, 8.6, 10.5 and 11.1;
find
(i) the mean ` barx `
(ii) the value of ` sum (x_i - barx)`
The mean of 100 observations is 40. It is found that an observation 53 was misread as 83.
Find the correct mean.
If the mean of observations x, x + 2, x + 4, x + 6 and x + 8 is 11,
find:
(i) The value of x;
(ii) The mean of first three observations.
The mean of 5 numbers is 18. If one number is excluded, the mean of the remaining number becomes 16. Find the excluded number.
Find the mean of 8, 12, 16, 22, 10 and 4. Find the resulting mean, if the observations, given above, be: divided by 2.
The mean of 40 observations was 160. It was detected on rechecking that the value of 165 was wrongly copied as 125 for computation of mean. Find the correct mean.
The mean of 100 items was found to be 30. If at the time of calculation two items were wrongly taken as 32 and 12 instead of 23 and 11, find the correct mean.
