AP EAMCET201825 Apr 2018Morning ShiftMathematicsStatisticsActual
The marks obtained by students A and B in 3 examinations are given below Marks of A 30 20 40 Marks of B 70 0 5 The ratio of the coefficient of variation of marks of A and the coefficient of variation of marks of B is
Options
- A3 :   1
- B5 : 8 3
- C1 :   3
- D5 : 3 61
Correct answer
D. 5 : 3 61
Step-by-step solution
The marks obtained by students A and B in 3 examinations are given below: Marks of A 30 20 40 Marks of B 70 0 5 Mean of A x ¯ = 30 + 20 + 40 3 = 90 3 = 30 Now, S.D. of A σ A = 1 n ∑ x i - x ¯ 2 = 1 3 30 - 30 2 + 20 - 30 2 + 40 - 30 2 = 200 3 Mean of B x ¯ = 70 + 0 + 5 3 = 75 3 S.D. of B σ B = 1 n ∑ x i - x ¯ 2 = 1 3 70 - 25 2 + 6 - 25 2 + 5 - 25 2 = 3050 3 Now, required ratio = σ A σ B × B x ¯ A x ¯ = 200 3 3050 3 × 75 3 30 = 5 3 61