MCA Entrance Previous Year Question Bank

Arrange the following in sequence to find the variance of individual observations:

(A) compute $ \bar{X} $ of observation $ x_1, x_2, \dots, x_n $

(B) square the deviation and obtain the sum $ \sum_{i=1}^{n} (x_i - \bar{X})^2 $

(C) divide the sum $ \sum_{i=1}^{n} (x_i - \bar{X})^2 $ by $ n $

(D) take the deviation of observations from the mean, that is $ (x_i - \bar{X}) $ where $ i = 1, 2, 3, \dots, n $

Mean and variance of 12 observation are $ \frac{9}{2} $ and 4 respectively later it was observed that two observation work consider 9 and 10 instead of 7 and 14 respectively. If correct variance is $ \frac{m}{n} $ where $ m $ and $ n $ are coprime then $ m + n $ is

The arithmetic mean and standard deviation of series of 20 items were calculated by a student as 20 cm and 5 cm respectively. But while calculating them an item 15 was misread as 30. Find the correct standard deviation.

The mean deviation from the mean of the A.P. $ a,, a+d,, a+2d,, \ldots,, a+2nd $ is

If each of n numbers $ x_{i} = i $ is replaced by $ (i + 1)x_{i} $ then the new mean is

If each observation of a Row data whose variance is $ \sigma^{2} $ is multiplied by h, then the variance of the new set is

Which of the following are ture

(A) Ogive graph is used to measure the median of the collection of datas.

(B) Two events A and B are such that P(A) = ½ and P(B) =7/2 and P(not A or not B) = ¼ then A and B are independent events.

(C) Relation for mean, mode and median is given by Mode= 3 Median – 2 Mean

(D) The number of two-digits even number formed from digits 1,2,3,4,5 is 10

Choose the correct answer from the options given below