Question

find the median of the following data class interval
11-15,16-20,21-25,26-30,31-35,36-40
frequency
3,5,9,12,7,4​

Answer 1

class । conti. class । fi । camulative fi
11-15 । 10.5 -15.5 । 3 । 3
16-20 । 15.5-20.5 । 5 । 3+5 =8
21 -25 । 20.5-25.5 । 9 । 8+9 = 17
26 -30 । 25.5-30.5 । 12 । 17+12=29
31 - 35 । 30.5 - 35.5 । 7 । 29+7 =36
36-40 । 35.5 - 40.5 । 4 । 36 +4 = 40
TOTAL :- । N =40।

N/2 = 40/2 =20
: . 20 is in the class 25.5-30.5
: . 25.5 - 30.5 is the median class
f = 12 , c.f = 17 , L = 25.5 , h= 5
median = L+ [ N/2 - c.f ] × h
[ / F ]

median = 25.5 + [ 20 - 17 / 12] × 5
median = 25.5 + [ 3/12 ] ×5
median = 25.5 + 1/4 × 5
median = 25.5 + 1.25
median = 26.75

therefore the median of given quastion is 26.75