Assignment 2 (i) The frequency distributions given below are incomplete determine the missing values (a) (b) C.I. F R.F. 0-2 ? 0.006 3-5 23 ? 6-8 ? 0.34 9-11 17 ? 12-14 ? ? 15-17 ? 0.08 100 (ii)Find the class boundaries, class marks and class widths for the following intervals: (a) 9 – 15 (b) (-7) – (-3) (c) 12.4 – 20.7 (d) 0.546 – 0.618 (e) (-2.75) – 1.35 (f) 80.49 – 88.72 (iii) Weekly price (x) of an item for a sample of 6 weeks is given as Rs. 24, 21, 29, 18, 26, 20 (i) find the mean price per week (ii) If y = 2x -3 find mean of y (iv) The mean of 12 observations is 37.4 one more observation is added and the mean become 37.5 find the value of new observation (v) The sum of the deviations of a certain number of observations measured from 4 is 72 and sum of deviations of the observations from 7 is -3. Find the number of observations and their mean. (vi) The sum of deviations of certain observations measured from 13 is 74. The sum of deviations of the same observations from 17 is -26. Find the number of observations and their mean. (vii) For a set of 9 numbers sum of squared deviations about AM is 60 and sum of squares of all observations is 285. Find the mean of the numbers. (viii) The weighted arithmetic mean of 3, 6, and 7 is 6. If the weights of first two observations are respectively 2 and 5, what is the weight of the third? f R.F. c.f. ? ? ? 21 ? 27 ? 0.38 65 19 0.19 84 ? ? ? 100 Dr. Akher
(ix) The GM and HM of two observations are respectively 18 and 10.8 find the observations (x) Combined variance can be computed as S= ?? ? ?? ? + = k i i i i n n D 1 2 2 2 (s ) s where i c i D = x – x and k n = n + n + … + n 1 2 A class of 150 students is divided into two groups containing 100 and 50 students respectively. The mean marks of the first group in Statistics are 60 and the mean marks of the second group are 90. The standard deviations of two groups are 4 and 6 marks respectively. Find the variance and standard deviation of all 150 students taken together (xi)…