JEE MATHEMATICS MCQ: STATISTICS

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The mean and SD of 63 children in an arithmetic test are respectively 27.6 and 7.1. They are added to a new group of 26 who had less training and whose mean is 19.2 and SD 6.2. The values of the combined group of the mean and SD are

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Correct option: A

25.1,7.8

Option A (25.1, 7.8) is correct because it accurately calculates the combined mean and standard deviation of the two groups using the provided data.

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If the mean of a set of observations

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

\bar X,

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{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

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