JEE MATHEMATICS MCQ: STATISTICS

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Analyzing +4 | -1

If the standard deviation of 10 observations

x_1, x_2, \ldots . ., x_{10}

is 4 and that of another set of 10 observations

y_1, y_2, \ldots \ldots y_{10}

is 3 and also

X_i=\left(x_i-\bar{x}\right)\left(y_i-\bar{y}\right) . \bar{x}

is mean of all

x_i

's and

\bar{y}

is mean all

y_i

's and

\sum\limits_{{i=1}}^{10} X_i=80

. Then standard deviation of observations

x_1-y_1, x_2-y_2, \ldots \ldots, x_{10}-y_{10}

View answer and explanation

Correct option: B

Option B (3) is correct because the standard deviation of the difference of two sets of observations can be found using the given standard deviations and the sum of the product of deviations from the means.

More Questions from STATISTICS

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If the mean of a set of observations

{x_1},{x_2}, \ldots ,{x_n}

\bar X,

then the mean of the observations

{x_i} + 2\;i;i = 1,\;2, \ldots ,n

is The sum of 10 items is 12 and sum of their squares is 18 , then standard deviation will be In a family, there are 8 men, 7 women and 5 children whose mean ages separately are respectively 24,20 and 6 years. The mean age of the family is The mean and variance of 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

1,3,5, x, y

are 5 observations. Mean of these observations is 5 and variance is 8. Sum of the cubes of the two missing number equals: If s.d. of a set of observations is 8 and if each observation is divided by

-2,

the s.d. of the new set of observations will be