Ex 14.3, 7 - Chapter 14 Class 10 Statistics

Transcript

Ex 14.3, 7 The distribution below gives the weights of 30 students of a class. Find the median weight of the students. Weight (in kg) Number of students Cumulative frequency 40 − 45 2 2 45 − 50 3 2+3=5 50 − 55 8 5 + 8=13 55 − 60 6 13+6=19 60 − 65 6 19+6=25 65 − 70 3 25+3=28 70 − 75 2 28+2=30 Median = l + (𝑛/2 −𝑐𝑓)/𝑓 × h n = ∑▒𝑓𝑖 𝑛/2 = 30/2 = 15 ∴ 55 – 60 is the median class l = lower limit of median class= 55 h = class-interval= 45 – 40 = 5 cf = cumulative frequency of the class before median class=13 f = frequency of the median class =6 Median = l + (𝑛/2 −𝑐𝑓)/𝑓 × h = 55 + (15 −13)/6 × 5 = 55 + 2/6 × 5 = 55 + 1.67 = 56.67 So, median weight is 56.67 kg