Given a table showing grouped data and the frequency of each class, find the median Q2

Step 1: Add a cumulative frequency column to the table

Step2: Use the formula n/2 (where n is the final total in the cumulative frequency column) to find the class the median, Q2, is in.

Let n/2= a, so that Qis in the class d<=y<e

because in the cumulative frequency column , b<a<c where b is the cumulative frequency of the class before d<=y<e and c the cumulative frequency of the class after

 

Step 3: Find the lower and upper class boundaries of the class that Q2 is in.

Q2 is the class d<=y<e.

Let class before d<=y<e  with cumulative frequency b be f<=y<g

Let the class after d<=y<e  with cumulative frequency c be  h<=y<i

Lower class boundary= l = (g+d)/2

Upper class boundary = u= (e+h)/2

 

 

Step 4: Interpolate to find Q

Using the following formula, the value of Q2 can be found:

(Q2-l) / (u-l) = (n/2-b) / (c-b)

 

We know from step 2

Qis in the class d<=y<e

b<a<c with n/2=a

b= the cumulative frequency of the class before the class Qis in

c= cumulative frequency of the class after the class Qis in

 

We know from step 3

 l=lower class boundary of the class d<=y<e

u= upper class boundary of the class d<=y<e

LS
Answered by Lesedi S. Maths tutor

9416 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

A straight line passes through the point (2,1) and has a gradient of 3. Find the co-ordinates where the line crosses the x and y axes


Express the equation cosecθ(3 cos 2θ+7)+11=0 in the form asin^2(θ) + bsin(θ) + c = 0, where a, b and c are constants.


Given that y = x^4 tan(2x), find dy/dx


The height x metres, of a column of water in a fountain display satisfies the differential equation dx/dt = 8sin(2t)/(3sqrt(x)), where t is the time in seconds after the display begins. (a) Solve the differential equation, given that x(0)=0


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences