Question 31 The median of the following data is 16. Find the missing frequencies a and b, if the total of the frequencies is 70.Given
โโ๐๐ = 70
Finding
Cummulative Freq.
Since
Median = 16
15 โ 20 is median class
Median = l + (๐/2 โ๐๐)/๐ ร h
Where
l = lower limit of median class
h = class-interval
n = โโ๐๐
cf = cumulative freq.of class before median class
f = frequency of the median class
Now,
Median = l + (๐/๐ โ๐๐)/๐ ร h
16 = 15 + (70/2 โ (24 + ๐))/15 ร 5
16 โ 15 = (35 โ 24 โ ๐)/3
1 = (11 โ ๐)/3
3 = 11 โ a
a = 11 โ 3
a = 8
Also,
โโ๐๐ = 55 + a + b
70 = 55 + a + b
Putting a = 8
70 = 55 + 8 + b
70 = 63 + b
70 โ 63 = b
b = 7

CBSE Class 10 Sample Paper for 2021 Boards - Maths Standard

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.