Answer :

For equal class intervals, we will solve by finding mid points of these classes using direct method.

We have got


Σfi = 63 + x + y and Σfixi = 2775 + 25x + 45y


mean is given by



( given: mean of pocket allowance is 42)


2646 + 42x + 42y = 2775 + 25x + 45y


42x – 25x + 42y – 45y = 2775 – 2646


17x – 3y = 129 …(i)


As given in the question, frequency(Σfi) = 100


And as calculated by us, frequency (Σfi) = 63 + x + y


Equalizing them, we get


63 + x + y = 100


x + y = 37 …(ii)


We will now solve equations (i) and (ii), multiply eq.(ii) by 3 and then add it to eq.(i), we get


(17x – 3y) + [3(x + y)] = 129 + 111


17x – 3y + 3x + 3y = 240


20x = 240


x = 12


Substitute x = 12 in equation (ii),


12 + y = 37


y = 37 – 12


y = 25


Thus, x = 12 and y = 25.


Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Arithmetic Progression and 'nth' Term of APArithmetic Progression and 'nth' Term of APArithmetic Progression and 'nth' Term of AP55 mins
Chemical Properties of Metal and Non MetalChemical Properties of Metal and Non MetalChemical Properties of Metal and Non Metal61 mins
Extraction of MetalExtraction of MetalExtraction of Metal56 mins
Purification of MetalsPurification of MetalsPurification of Metals60 mins
Properties of Metal and Non MetalProperties of Metal and Non MetalProperties of Metal and Non Metal59 mins
Introduction of Metal and Non MetalIntroduction of Metal and Non MetalIntroduction of Metal and Non Metal59 mins
Trigo Marathon Part 2Trigo Marathon Part 2Trigo Marathon Part 245 mins
Application of Trigo Important QuestionsApplication of Trigo Important QuestionsApplication of Trigo Important Questions44 mins
Outcomes of DemocracyOutcomes of DemocracyOutcomes of Democracy43 mins
Trigo Marathon Part 1Trigo Marathon Part 1Trigo Marathon Part 146 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses