NDA || Mathematics || Statistics || Quiz 2020

The standard deviation of n observations ,……… is 10.The standard deviation of another set of n observations ,……… is 15. What is the standard deviation of n observation ,?

In a partially destroyed record the following data are available :

Regression equation of x on y and regression equation of y on x are 3x+y=12 and x+2y=14 respectively then find the sum of mean values of x and y.

The variance of 20 observations is 5. If each observation is multiplied by 3, then what is the new variance of the resulting observations?

The mean of a group of 100 observations was found to be 20.Later it was found that four observations were incorrect, which were recorded as 21, 21, 18 and 20. What is the mean if the incorrect observations are omitted?

If the data are moderately non-symmetrical, then which one of the following empirical relationships is correct?

A sample of 5 observations has mean 32 and median 33.Later it is found that an observation was recorded incorrectly as 40 instead of 35. If we correct the data, then which one of the following is correct?

Consider the following statements :

1) The mean and median are equal in symmetric distribution.

2) The range is the difference between the maximum value and minimum value in the data.

3) The sum of the areas of the rectangles in the histogram is equal to the total area bounded by the frequency polygon and the horizontal axis.

Which of the above statements are correct?

The scores of 15 students in an examination were recorded as 10, 5, 8, 16, 18, 20, 8, 10, 16, 20, 18, 11, 16, 14 and 12. After calculating the mean, median and mode, an error is found. One of the values is wrongly written as 16 instead of 18. Which of the following measures of central tendency will change?

For 10 observations on price (x) and supply (y), the following data was obtained :

  and

what is the line of regression of y on x?

In a study of two groups, the following results were obtained:

Which of the following statements is correct?