help for me 14 th question
Answers
If the median of the following data is 32.5, find the missing frequencies.
Class interval:
0−10
10−20
20−30
30−40
40−50
50−60
60−70
Total
Frequency:
f1
5
9
12
f2
3
2
4
Ask for details FollowReport by BrainlyHelper 17.01.2019
Answers
Balaronaldo77
Balaronaldo77 · Ambitious
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nikitasingh79
Nikitasingh79 ★ Brainly Teacher ★
SOLUTION :
CUMULATIVE FREQUENCY TABLE is in the attachment.
Given : Median = 32.5 , which belongs to the class 30 - 40 . So the Median class is 30 - 40
Given : n(Σfi) = 40
Here, n = 40
n/2 = 20
From the table , l = 30, f = 12, cf = (14 + f1) , h = 10
MEDIAN = l + [(n/2 - cf )/f ] ×h
32.5 = 30 +[ 20- (14+f1)/12] ×10
32.5 - 30 = [(20- 14 + f1)/12] ×10
2.5 =[ (6 - f1)/12 ]×10
2.5 × 12 = 60 -10 f1
30 - 60= -10f1
-30 = -10f1
f1 = 30/10 = 3
f1 = 3
Given : Σfi = 40
31 + f1 + f2 = 40 [from the table]
f1 + f2 = 40 - 31
3 + f2 = 9 [f1 = 3]
f2 = 9 - 3
f2 = 6
Hence, the missing frequencies be f1 = 3 and f2 = 6
★★ MEDIAN = l + [(n/2 - cf )/f ] ×h
Where,
l = lower limit of the median class
n = number of observations
cf = cumulative frequency of class interval preceding the median class
f = frequency of median class
h = class size
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