JEE MATHEMATICS MCQ: STATISTICS

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Application +4 | -1

The mean marks of students of a school is 56 . The mean marks of girls is 60 and that of boys is 50. If number of boys and girls are

n

and

m

respectively, then

\frac{9 n}{m}

equals

View answer and explanation

Correct option: D

Option D (6) is correct because it is derived from setting up a weighted average equation for the mean marks of the school and solving for the ratio n/m.

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If the mean of a set of observations

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\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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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