JEE MATHEMATICS MCQ: STATISTICS

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The mean weight of 150 students in 60 Kgs. The
mean weight of boys is 70 and that of girls in 55
with standard deviations 10 and 15 respectively. The
combined variance is

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Correct option: A

\frac{700}{3}

Option A (700/3) is correct because it is the result of applying the combined variance formula, considering the number of students, means, and standard deviations for both boys and girls.

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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