Advertisements
Advertisements
प्रश्न
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.
Advertisements
उत्तर
Here,
n = 100, X = 30.
So, `bar"X" = (1)/"n"(sumx_i)`
⇒ `sumx_i = "n"bar"X"`
⇒ `sumx_i` = 100 x 30 = 3000.
∴ Incorrect value of" `sumx_i` = 3000
Now, correct value of
`sumx_i = "Incorrect value of" sumx_i` - (Sum of incorrect values) + (Sum of correct values)
= 3000 - (32 + 12) + (23 + 11)
= 2290.
∴ Correct mean
= `("Correct value of" sumx_i)/"n"`
= `(2990)/(100)`
= 29.9.
संबंधित प्रश्न
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.
Find x if 9, x, 14, 18 x, x, 8, 10 and 4 have a mean of 11.
Find the mean of 75 numbers, if the mean of 45 of them is 18 and the mean of the remaining ones is 13.
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.
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.
The mean of 5 numbers is 18. If one number is excluded, the mean of the remaining number becomes 16. Find the excluded number.
The mean of 16 numbers is 8. If 2 is added to every number, what will be the new mean?
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.
If `bar"X"` is the mean of n observations x1, x2, x3,..., xn then the mean of `x_1/"a", x_2/"a", x_3/"a",...,x_"n"/"a" "is" bar"X"/"a"`, where a is an non-zero number.
i.e., if each observation is divided by a non-zero number, then the mean is also divided by it.
