The cumulative frequency just greater than N2 is 65 then median class is 70−90 such that,
l=70,h=90−70=20,f=22,cf=43
Median=l+N2−cff×h
⇒ Median=70+50−4322×20
⇒ Median=70+7×2022
⇒ Median=70+6.36
∴ Median=76.36
(ii)
Class interval | Frequency | Cumulative Frequency |
80−90 | 9 | 9 |
90−100 | 17 | 26 |
100−110 | 19 | 45 |
110−120 | 45 | 90 |
120−130 | 33 | 123 |
130−140 | 15 | 138 |
140−150 | 12 | 150 |
150−160 | 0 | 150 |
| N=150 | |
We have,
N=150, then,
N2=1502=75
The cumulative frequency just more than N2 is 90 then the median class is 110−120 such that
l=70,h=120−110=10,f=45,cf=45
Median=l+N2−cff×h
⇒ Median=110+75−4545×10
⇒ Median=110+30×1045
⇒ Median=110+6.67
∴ Median=116.67