Question : The mode of the following data is 154. Find the value of m. Also find median of following data.
Class Intervals | 120-130 | 130-140 | 140-150 | 150-160 | 160-170 |
Frequency | 2 | 8 | m | 20 |
8
|
Doubt by Parth
Solution :
Mode = 154
Modal Class = 150-160
l=150
h=160-150=10
f0=m
f1=20
f2=8
Mode = l+{[f1-f0]/[2f1-f0-f2]}×h
154 = 150+{[20-m]/[2(20)-m-8]}×10
154-150= {[20-m]/[40-m-8]}×10
4/10 = {[20-m]/[32-m]}
2/5 = [20-m]/[32-m]
2[32-m] =5[20-m]
64-2m=100-5m
5m-2m=100-64
3m=36
m=36/3
m=12
Median of the Data
Class Intervals (CI) | Frequency (fi) | Cumulative Frequency (CF) |
120-130 | 2 | 2 |
130-140 | 8 | 10 |
140-150 | 12 | 22 |
150-160 | 20 | 42 |
160-170 | 8 | 50 |
N=Σfi=50 |
Here
N=Σfi=50
N/2 = 50/2 = 25
N/2 = 50/2 = 25
Median class = 150-160
l=150
h=160-150=10
CF=22
f=20
CF=22
f=20
Median = l+{[(N/2)-CF]/[f]}×h
Median = 150+{[25-22]/[20]}×10
Median = 150+30/20
Medina = 150+3/2
Median = 150+{[25-22]/[20]}×10
Median = 150+30/20
Medina = 150+3/2
Median = 150+1.5
Median = 151.5
Median = 151.5