Advertisements
Advertisements
Question
Find the mean of 75 numbers, if the mean of 45 of them is 18 and the mean of the remaining ones is 13.
Advertisements
Solution
Mean of 45 numbers = 18
⇒ Sum of 45 numbers = 18 x 45 = 810
Mean of remaining ( 75 - 45 ) 30 numbers = 13
⇒ Sum of remaining 30 numbers = 13 x 30 = 390
⇒ Sum of all the 75 numbers = 810 + 390 = 1200
⇒ Mean of all the 75 numbers = `1200/75` = 16
APPEARS IN
RELATED QUESTIONS
Find the mean of the first ten odd natural numbers.
Find the mean of all factors of 10.
Find x if 9, x, 14, 18 x, x, 8, 10 and 4 have a mean of 11.
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.
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.
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.
