EASY
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IMPORTANT
Earn 100

The mean and variance of 20 observations are found to be 10 and 4, respectively. On rechecking, it was found that an observation 9 was incorrect and the correct observation was 11, then the correct variance is

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Important Questions on Statistics

HARD
JEE Main
IMPORTANT
Let the observation xi1i10 satisfy the equations  i=110xi-5=10, i=110xi-52=40 . If μ and λ are the mean and the variance of the observations, x1-3,x2-3,....,x10-3, then the ordered pair μ,λ is equal to
MEDIUM
JEE Main
IMPORTANT
If the standard deviation of the numbers -1, 0, 1, k is 5 where k>0, then k is equal to
EASY
JEE Main
IMPORTANT
The mean and the median of the following ten numbers in increasing order 10, 22, 26, 29, 34, x, 42, 67, 70, y are 42 and 35 respectively, then yx is equal to:
MEDIUM
JEE Main
IMPORTANT
5 students of a class have an average height 150 cm and variance 18 cm2. A new student, whose height is 156 cm, joined them. The variance in cm2 of the height of these six students is:
MEDIUM
JEE Main
IMPORTANT
A data consists of n observations: x1, x2,  , xn. If i=1nxi+12=9n and i=1nxi-12=5n, then the standard deviation of this data is
MEDIUM
JEE Main
IMPORTANT
The mean and variance for seven observations are 8 and 16 respectively. If 5 of the observations are 2,4,10,12,14, then the product of the remaining two observations is
EASY
JEE Main
IMPORTANT
A student scores the following marks in five tests: 45,54,41,57,43. His score is not known for the sixth test. If the mean score is 48 in the six tests, then the standard deviation of the marks in six tests is
MEDIUM
JEE Main
IMPORTANT

If for some xR, the frequency distribution of the marks obtained by 20 students in a test is:

Marks 2 3 5 7
Frequency distribution x+12 2x-5 x2-3x x

Then the mean of the marks is :